Some patients with hematologic malignancies as acute lymphoblastic leukemia (ALL), can achieve complete remission (CR) after chimeric antigen receptor T cell (CAR-T) immunotherapy. However, many constraints still limit the wide application of CAR-T immunotherapy in patients with hematological malignancies and other cancers, especially in patients with solid tumors. The main challenges related to CAR-T immunotherapy include: relapse caused by immune escape of tumor antigens, cytokine release syndrome (CRS), poor survival timein vivo,low infiltration capacity and inactivation of CAR-T in solid tumors, etc.. This article summarizes effects and problems of CAR-T immunotherapy in clinical trials for hematological malignancies, and how to use comprehensive treatment and biotechnology strategies to solve the current problems, in order to improve safety and effectiveness of CAR-T immunotherapy, and expand clinical benefits of CAR-T immunotherapy for patients with different tumors.