The invention relates to a chimeric antigen receptor based on CD20, and applications thereof, and more specifically relates to a cell technology construction method of chimeric antigen receptor T (CAR-T) taking tumor specific target spot CD20 as a base, and applications of the chimeric antigen receptor T in treatment of tumor. The chimeric antigen receptor T is composed of an antigen binding domain, a transmembrane domain, a costimulatory signal transduction region, and a CD3 zeta signal transduction domine via series connection; wherein the antigen binding domain is used for binding tumor surface antigens, and the tumor surface antigen is CD20. According to applications, specific gene modification of single-chain antibody of tumor surface antigen CD20 is carried out, the modified antibody is capable of increasing antigen-antibody binding force, mutation is not easily caused. Compared with other chimeric antigen receptors and other tumor antigens, the chimeric antigen receptor possesses following advantages: the effect is better, target spot expression quantity is higher, immune effect on CAR-T cells is improved, and treatment effect of CAR-T cells is improved.