The invention relates to a chimeric 
antigen acceptor of a target BCMA (
B cell maturation 
antigen). The chimeric 
antigen acceptor comprises an 
extracellular identification region, a 
hinge region, a 
transmembrane region and an 
intracellular signal region, wherein the 
extracellular identification region has a BCMA resisting nanometer 
antibody sequence, and the BCMA resisting nanometer 
antibody sequence is a heavy-chain variable region sequence combining with BCMA and from alpacas. More specifically, the BCMA resisting nanometer 
antibody sequence is BCMA 
monoclonal antibody B1 or B65, the 
amino acid sequence of the B1 is as shown in SEQID NO.1, and the 
amino acid sequence of the B65 is as shown in SEQID NO.2. According to the chimeric antigen 
acceptor disclosed by the invention, compared witha traditional mouse-derived SCFV or humanized SCFV, the nanometer antibody from the alpacas is used, and has 
small molecule quantity and 
immunogenicity, the possibility that CAR-T cells prepared on the base of the nanometer antibody produce HAMA effects 
in vivo is smaller, the remaining time of the CAR-T cells 
in vivo can be longer, the CAR-T cells pass through BCMA 
protein on the surfaces of target 
tumor cells and activate 
signal channels at the downstream part of T cells, the capacity for killing 
tumor cells having BCMA target points is given to the T cells, and BCMA positive 
blood tumor canbe efficiently and specifically treated.