Although some progress has been made in cancer treatment, there are still challenges such as tumor cell escape and recurrence after treatment. This article analyzed tumor surface antigens and their specificity, and designed antigen receptors for Chimeric Antigen Receptor T-Cell (CAR-T) targeting tumor cells. This article intended to use gene encoding techniques such as CRISPR-Cas9 (clustered regularly interspaced short palindromic repeats-associated protein 9) to precisely regulate CAR-T cells and improve their therapeutic efficacy. On this basis, using in vitro amplification, culture and other methods, the large-scale production of CAR-T cells was achieved to ensure the sustained and stable therapeutic effect. This article tracked the therapeutic effects of mouse models and clinical trials on patients for a long time, and evaluated the persistence and stability of CAR-T combined with immunosuppressive agents. The survival time of CAR-T cells in vivo and their long-term inhibitory effect on tumors were analyzed. After using CAR-T treatment, the survival time of CAR-T cells was 120 days. The recurrence time of the tumor was 180 days, which was significantly longer than the 30 days in the tumor control group, indicating that CAR-T treatment has a certain effect on delaying tumor recurrence. This article comprehensively evaluated the efficacy and mechanism of CAR-T combined with immunosuppressive agents in tumor treatment, providing important scientific basis and experimental support for future clinical applications.