Abstract: Chimeric antigen receptor T cell (CAR-T) therapy has produced remarkable results in the treatment of hematological tumors. The BCMA antigen is widely expressed on the surface of multiple myeloma cells and is a suitable, efficient target for CAR-T therapy. BCMA CAR-T cell therapy has a high response rate for relapsed or refractory patients in particular, and CAR-T cells are still detectable in most patients 1 year after infusion. However, drug resistance and disease recurrence remain key problems in clinical management. In this paper, we discuss the response factors and resistance induction mechanism of BCMA CAR-T cell therapy from several perspectives, such as the immune escape of multiple myeloma cells, CAR-T product factors, previous treatment regimens, and tumor immune microenvironment inhibition. We also propose possible optimization strategies in order to provide reference for future exploration.