Abstract: There is still a lack of clear regulations in China on how to handle internal conflicts of interest among joint litigants. At present, the applicable legal principles of the "common principle" need to be clarified, the internal relationship of necessary joint litigation adopts the "consensus principle", and the court can forcibly add necessary joint litigation plaintiffs, which leads to varying degrees of difficulties in effectively coordinating and balancing the interests of internal opposing joint litigation parties, whether it is ordinary joint litigation or necessary joint litigation. In the era of the Civil Code, based on respect for the independence and autonomy of joint litigants as civil subjects, procedural safeguards in the application of the "common principle" in ordinary joint litigation should be strengthened, and consistent with the cautious application of necessary joint litigation in the Civil Code, limiting the scope of application of necessary joint litigation. In terms of the system, efforts should be made to narrow down the situation of mandatory addition of joint plaintiffs, granting the added plaintiffs basic procedural safeguards and remedies, and transforming the "principle of consensus through negotiation" in the necessary internal relationships of joint litigation into a "favorable theory".