Abstract: In this article, the main components of lignin, cellulose, brown pigment, and lignin during the development of walnut endocarp, as well as the influencing factors were summarized. Based on the induction, summary, and comparative analysis of relevant literature at home and abroad, the existing research were sorted out. The effects of lignin, cellulose and brown pigment, and the environmental factors of lignin synthesis during the development of walnut endocarp, the cloning and expression analysis of lignin synthesis-related enzymes and related genes during lignin metabolism were reviewed. It is expected that the research results will provide basic reference for the in-depth study of the formation mechanism of walnut endocarp and the formulation of reasonable breeding management measures in production practice to reduce the occurrence of kernel exposure and fruit cracking.