Abstract: Claim is a legal way for the children born out of wedlock to be legitimate children, and it, together with other regulations, such as presumption of maternity or paternity, denial of maternity or paternity, legislation and so on, constitutes a complete legal system of maternity or paternity. However, the Civil Code of the People’s Republic of China only provides general provisions on claim system, and does not specify the actual operation norms of the facultative claim, mandatory claim, denial of maternity or paternity, and legitimation. The legal system of claim in Germany and Switzerland can provide a good reference for the improvement of the applicable rules of claim in the Civil Code of China. The interpretation and application of the claim system should be based on the necessity of blood relationship, maintain the identity stability of children born out of wedlock, and keep in line with the best interests of children to ensure the kinship rights and interests of children born out of wedlock. Therefore, this paper aims to provide theoretical support and combine practical experience to accurately understand and apply the claim system.