The invention relates to a target BCMA chimeric antigen receptor, a nucleic acid sequence, a carrier and an application, and a composition and a method for treating cancers using CAR cells. The composition comprises the isolated nucleic acid sequence for coding a CAR, wherein the CAR comprises an extracellular structure domain, a transmembrane structure domain and an intracellular structure domain; the extracellular structure domain is bound with a BCMA; the isolated nucleic acid sequence includes the nucleic acid sequence as shown in SEQ ID NO: 1, 2 or 9; the intracellular structure domain comprises a co-stimulation signal conduction region; and the co-stimulation signal conduction region comprises molecules selected from CD27, CD28, 4-1BB, OX40, CD30, CD40, PD-1, ICOS, lymphocyte function-related antigen-1(LFA-1), CD2, CD7, LIGHT, NKG2C, B7-H3 and any combination thereof.