The Princess Weiyoung

• Tiffany Tang as Li Wei Yang / Feng Xin'er
  • Kind, bright and intelligent, she seeks to investigate the truth after her kingdom is destroyed and her family is assassinated. Being, in reality, the princess of Northern Liang, she assumed her friend Weiyoung's identity as the illegitimate daughter of Prime Minister Li, in order to be able to avenge her own family as well as Weiyoung. In the process she falls in love with the Emperor's grandson without knowing his status at first, then tries to rebuff him when she realizes who he is. In the end, Weiyoung became Tuoba Jun's wife, and bore him a son. After Tuoba Jun's death ten years after the events in the drama, she became the Empress Dowager with their young son ascending the throne.
• Luo Jin as Tuoba Jun, Prince Gaoyang
  • Bright, sunny and compassionate, Tuoba Jun is the Emperor's favorite grandson as well as the deceased Crown Prince's son. As a result, he is targeted by the Emperor's sons, Tuoba Han and Tuoba Yu. However, he doesn’t care about royal politics. His sincerity and unwavering love towards Weiyoung, despite her desire for revenge, makes her fall for him. In the end, he finally became Weiyoung's husband and together they have a son, and Tuoba Jun ascends the throne as Emperor. Tuoba Jun eventually dies from an illness ten years after the events in the drama.
• Vanness Wu[11] as Tuoba Yu, Prince Nanan
  • Cunning, ruthless and cold-blooded, Tuoba Yu's greatest ambition is to become the Emperor and rule the world. He is attracted by Weiyoung's intelligence and wit, and plans to use her as a chess piece to realize his ambitions. However, he soon falls for her, and is willing to go to extreme lengths to have her by his side.
• Mao Xiaotong[12] as Li Changru, Daughter of the 2nd aunt of the Li Family. Weiyoung's younger cousin.
  • She has been in love with Tuoba Yu since she was young. Having been oppressed and overshadowed by her elder cousin Li Changle from a young age, she becomes ruthless and seeks to topple her cousin. She hides her hypocritical and scheming nature behind her weak and delicate appearance. She treats Weiyoung sincerely at first, but turns against her when she discovered that Tuoba Yu has fallen for her, and as a result she betrays Weiyoung. She eventually becomes pregnant with Tuoba Yu's child. Nearing the end of the series, Changru tries to kill Weiyoung but only resulted in killing Tuoba Yu. She then killed herself out of misery for inadvertently causing Tuoba Yu's death.
• Li Xinai[13] as Li Changle, Daughter of Chiyun Rou and Li Xiaoran. Wei yang's older half-sister.
  • Known as the #1 beauty in the capital province, she is arrogant and selfish, believing that no woman is better than her. The appearance of Li Weiyoung makes her insecure and jealous. She seeks to get rid of Weiyoung and marry Tuoba Jun on whom she has had a crush for a long time. After she frames Li Weiyoung for the death of the Crown Princess (Tuoba Jun's mother), she eventually becomes the wife of Tuoba Jun. After it was discovered that she was the real murderer, she has to kill herself as punishment.

• Canti Lau[14] as Tuoba Tao, Emperor Taiwu of Northern Wei. He was betrayed by Zong Ai at the end.
• Wan Meixi[15] as Empress of Northern Wei
• Ding Ziling[16] as Lu Zhaoyi
  • Tuoba Tao's concubine and Tuoba Yu's mother.
• Wang Yujing as Tuoba Huang, former Crown Prince.
  • Tuoba Jun's deceased father. He was framed by Zong Ai as well as Tuoba Yu, imprisoned by the Emperor, and dies of acute illness shortly after.
• Xu Rongzhen[17] as Crown Princess, Tuoba Jun's mother.
• Zhang Tianyang[18] as Tuoba Han, Prince Dongping
  • He tries to murder Tuoba Jun on the hunting grounds by setting a hidden trap, which Changle uses as well to get rid of Weiyoung after discovering it. In an attempt to take down Tuoba Yu, who he saw as a threat in his ambitions to become the successor, Tuoba Han frames Weiyoung for attempting to poison the Empress. When the truth of all his schemes and the collusion with local authorities to enclose lands for personal gains was exposed, the Emperor was about to have him and those involved executed, but instead he was banished as a civilian and confined in his own manor.
• Chen Yuqi[19] as Tuoba Di, Ninth Princess
  • She initially dresses as a man to make fun of Li Minde, thinking he was the one who wanted her hand in marriage. After learning archery and spending time with him, she falls in love with him. Although her love was initially not reciprocated, she takes it in stride and continued to help Li Minde protect Weiyoung. In the end, she gets together with Li Minde after nearly losing her life.
• Hou Ruixiang as Zong Ai, The Emperor's personal eunuch.
  • He is actually Tuoba Yu's underling, bribed when Tuoba Yu was 13. He is discovered for his betrayal after trying to steal the account record that proved the Crown Prince's innocence. This also results in him killing Emperor Taiwu.
• Meng Fei as Gao Yun
  • Stood up for Tuoba Jun in court, and pleaded Yu for his innocence. Ultimately submits to Yu, but he still remains loyal to Tuoba Jun.
• Rui Weihang[20] as Cheng De, Tuoba Jun's subordinate. He likes Jun Tao.
• Wu Hong[21] as Cheng An, Tuoba Yu's subordinate.
• Zhang Yuechi as Jiang Zuo, Tuoba Han's subordinate.
• Guan Shan as Qiu Yi, Personal servant of Crown princess.
• Jiang Zhen as Xiaolinzi
• Liu Fenggang as Physician Liu
• Han Yan as Head Attendant Liang
• Li Jiaxi as Cai Ping

• Wang Liyuan as Old Granny Li, Li Weiyoung's grandmother.
  • She is one of the few members of the Li household who continually stands up for and cherishes Weiyoung, even after learning her identity.
• Bai Fan[22] as Li Xiaoran,
  • Prime Minister of Northern Wei. Li Weiyoung's father. Abandons her after realizing her true identity.
• Lily Tien[23] as Chiyun Rou
  • First lady of the Li family. Li Xiaoran's wife; Li Minfeng and Li Changle's birth mother. An evil woman from the Chiyun family who conspires to kill Weiyoung so that she will not overshadow Changle and ruin their plans. She dies from poisoning herself in a scheme to get rid of Weiyoung.
• Hu Caihong[22] as Wen Weiyi
  • Second lady of the Li Family. Li Changru and Li Changxi's birth mother. Also a cunning and arrogant woman.
• Wang Wanjuan as Zhou Xuemei
  • Third lady of the Li Family. Li Minde's adoptive mother. She is killed by Chiyun Rou, who plotted to deliberately infect her with a highly contagious disease.
• Liu Jie[24] as Seventh Madame
  • Li Weiyoung's birth mother. A kind woman, she discovers that Xin'er is not the real Weiyoung but helps keep her secret, and decides to consider Xin'er as her daughter after she confronts her with the truth.
• Nan Fulong as Li Minfeng
  • Eldest son of the Li family. He is power-hungry, lustful, and manipulative. He uses Zi Yan to harm Weiyoung, and dumps her after that. He is killed by Jun Tao after an elaborate plot set up by Weiyoung to avenge Zi Yan's death at his hands.
• Li Yixiao as Li Weiyoung (real)
  • Second mistress of the Li household. She was thrown out of the Li household as she was born on an inauspicious date. Li Weiyoung saves Feng Xin'er's life and is killed not long after. After Weiyoung's death, Xin'er assumes her identity to avenge both the murder of her father and grandmother, and also Weiyoung herself.
• Peng Doudou[25] as Li Changxi
  • Fourth young mistress of the Li family. She likes to eat, and often sucks up to Li Changle.
• Zhou Meiyi[26] as Chun Ming
  • Chiyun Rou's accomplice and personal servant.
• Mu Le'en[27] as Bai Zhi
  • Li Weiyoung's loyal servant. She later dies at the hands of Li Changru.
• Tian Yixi[28] as Zi Yan
  • Li Weiyoung's personal servant. She betrays Weiyoung after being manipulated by Li Minfeng. She becomes pregnant with his child, and ends up in his household where she is mistreated daily by him. She was rescued by Zhou Xuemei, and died in Weiyoung's arms.
• Peng Yingying[29] as Cui'er, Seventh Madame's personal servant.
• Jin Pohan as Rong'er
  • Li Changru's loyal servant who is her accomplice in killing Bai Zhi.
• Chang Shixin as Tan Xiang, Li Changle's personal servant.
• Wang Tianhong as Liu Hong, Li Changxi's personal servant.
• Dai Chunrong as Madame Liu, Li Weiyoung's caretaker.
  • She mistreats Weiyoung and after her death, agrees to help pass Xin'er off as Weiyoung to prevent her family from being harmed. She later betrays Xin'er and reveals the deception after being threatened by Chiyun Rou.
• Zhu Xingyu as Ping An, Li Minde's subordinate.
• Tan Songmei as Mother Luo, Old Granny Li's personal servant.

• Tang Jiayang as Old Granny Chiyun
• Jin Han[30] as Chiyun Nan
  • Great general of Northern Wei. Chiyun Rou's nephew. He plotted and framed King Hexi of Northern Liang for rebellion in order to satisfy his greed. He eventually works for Tuoba Yu after he saves his life.
• Ji Xiaobing as Chiyun Si
• Zhang Shenghao as Chiyun Wei
• Yang Zuqing[31] as Hong Luo
  • Chiyun Nan's faithful follower who is in love with him.

• Leanne Liu as Queen Dowager
  • Feng Xin'er's loving grandmother who sacrifices herself to protect her granddaughter.
• Tan Kai as King Hexi of Northern Liang
  • Feng Xin'er's father who was framed for staging a coup and killed by Chiyun Nan.
• Sun Wei[32] as Uncle Ming
  • Head of the royal guards. Jun Tao's father. He killed by Chiyun Nan.
• Wang Yanzhi[33] as Jun Tao
  • Feng Xin'er's royal bodyguard. She later continues to stay by her side as a confidante, after Xin'er assumed Weiyoung's identity. She likes Cheng De.
• Zhang Hengping as Fortune Teller Monk

• Liang Zhenlun[34] as Li Minde / Prince Yuan Lie, Crown Prince of Rou Ran under Tuhezhen Khan
  • He was adopted as the second young master of Li Family by Zhou Xuemei. He likes Weiyoung initially, but later falls for Tuoba Di.
• Wang Wei[35] as Princess An Le, Yuan Lie's younger sister.
• Li Ang[36] as General Jiao
  • Minister of Rou Ran Kingdom. He secretly trails and protects Li Minde / Yuan Lie.

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The author of the source novel was involved in a plagiarism case, where it was alleged that she used a software to copy over hundreds of other works to write her own novel. An alliance formed by 12 writers, including famed wuxia novelist Woon Swee Oan, joined together to sue Qin Jian.[9][38] According to Beijing News, a group of volunteers compared The Poisonous Daughter (Chinese: 庶女有毒) with more than 200 other novels. They found that out of 294 chapters, only nine chapters were original.[7]

On May 8, 2019, the Chaoyang District People's Court has declared Qin Jian guilty of infringing the works of Shen Wenwen, who wrote the novel 身历六帝宠不衰 that The Poisonous Daughter was copied from. Qin Jian has to compensate Shen Wenwen a total amount of CN¥136,500 ($20,000) for economic loss and intellectual copyright protection within 10 days of the verdict. Moreover, she must immediately cease sales and distribution of the novel upon the day the sentence is handed down.[8]