The invention belongs to the technical field of 
biology, and discloses a polypeptide containing two 
chimeric antigen receptor structures, 
nucleic acid for coding the polypeptide, a modified 
T lymphocyte, and a preparation method and application of the 
T lymphocyte. The polypeptide provided by the invention contains the two 
chimeric antigen receptor (CAR) structures, wherein one 
chimeric antigen receptor structure specifically targets a tumor 
cell, and the other one specifically targets a normal B 
lymphocyte, so that a CAR-
T cell is effectively amplified through recognizing the B 
lymphocyte ofa 
blood circulation system, and more CAR-T cells arrive at a 
solid tumor part so as to specifically kill the tumor 
cell for improving a 
treatment effect on the 
solid tumor. The polypeptide further comprises an ScFv structure of an anti-PD-L1 
monoclonal antibody, and the CAR-T cells can simultaneously secrete a PD-L1 
monoclonal antibody which interdicts an immunosuppressive action medicated by a PD1 / PDL1 
signal pathway and 
T cell failure, so that the 
treatment effect on the 
solid tumor is improved, the 
functional activity of immune cells 
in vivo is prolonged at the same time, and finally the 
tumor recurrence is retarded and even avoided.