▎ 摘　　要

NOVELTY - Constructing chimeric antigen receptor modified cell library involves transfecting first gene element, second gene element, third gene element, fourth gene element and fifth gene element into cell, where carrier is one or more, namely obtaining chimeric antigen receptor modified cell library. The first gene element is nucleotide sequence encoding receptor 1 comprising extracellular domain, transmembrane domain and intracellular domain. The extracellular domain identifies biotin or 6*His label marked on target antigen, intracellular domain comprises tobacco etch virus protease (TEVP). The second gene element is nucleotide sequence encoding receptor 2 comprising extracellular antigen-binding domain, transmembrane domain and intracellular signal domain. The antigen-binding domain is antibody sequence dynamic library. The dynamic library is induced under action of fourth gene element to generate series mutation, where introduction sequence diversity is obtained. USE - Method for constructing chimeric antigen receptor modified cell library used for preparing antibody aiming at specific target antigen (claimed), in antigen-binding domain automatic optimization, and preparing multiple antibodies. ADVANTAGE - The method enables to have more convenient and efficient operation. DETAILED DESCRIPTION - Constructing chimeric antigen receptor modified cell library involves transfecting first gene element, second gene element, third gene element, fourth gene element and fifth gene element into cell, where carrier is one or more, namely obtaining chimeric antigen receptor modified cell library. The first gene element is nucleotide sequence encoding receptor 1 comprising extracellular domain, transmembrane domain and intracellular domain. The extracellular domain identifies biotin or 6*His label marked on target antigen, intracellular domain comprises tobacco etch virus protease (TEVP). The second gene element is nucleotide sequence encoding receptor 2 comprising extracellular antigen-binding domain, transmembrane domain and intracellular signal domain. The antigen-binding domain is antibody sequence dynamic library. The dynamic library is induced under action of fourth gene element to generate series mutation, where introduction sequence diversity is obtained. The intracellular signal domain comprises tTA transcription factor domain and connection sequence. The connection sequence is connected with tTA transcription factor domain and transmembrane domain, comprising TEVP capable of identifying sequence of cutting. The third gene element is nucleotide sequence encoding screening gene, where tTA transcription factor can start expression of screening gene, host generates fluorescence to obtain certain resistance, or growth advantage to obtain certain condition. The fourth gene element is nucleotide sequence encoding cis-regulatory elements and transacting factors. The cis regulatory element makes DNA generate special structure of DNA sequence. The special structure is DNA structure containing no base complementary pairing of DNA single chain structure. The special structure comprises R-loop, G-triplet and G-quadruplex. The trans-acting factor is variant of clustered regularly interspaced short palindromic repeats (CRISPR) associated protein (Cas) protein family and Cas protein family, guide RNA (gRNA), uracil glycosylase inhibitor, adenine deaminase, cytidine deaminase, RNA-DNA hybrid chain binding protein, photosensitive protein, Nucleolin, DNA helicase, error-prone DNA polymerase, recombinant enzyme, endonuclease, nucleic acid exonuclease, alkyl adenine glycosylase. The fifth gene element is nucleotide sequence of coding inhibiting system, tTA transcription factor can start expression of inhibiting system to knock down or knock out trans-acting factor, where antibody sequence dynamic library is stable. The fifth gene element is nucleotide sequence encoding light control system, light control system can control expression of fourth gene element. The fourth gene element is started under illumination condition to construct antibody dynamic sequence library, after stopping illumination, fourth gene element function is inhibited, antibody dynamic sequence library is stable. INDEPENDENT CLAIMS are included for: 1. a method for screening chimeric antigen receptor modified cell library of antigen-binding domain automatic optimization, which involves: a. preparing target antigen, marking target antigen with label capable of getting identified by receptor 1, where label comprises biotin or 6*His; b. performing target antigen and chimeric antigen receptor modified cell culture incubation, and according to expression condition of screening gene, screening positive chimeric antigen receptor expression cell; and c. amplifying and sequencing chimeric antigen receptor extracellular antigen binding domain of positive cell to obtain antibody nucleotide sequence capable of specifically binding to target antigen; and 2. an antibody, which is obtained by screening method.