Objective: In gastric cancer cells, the influence of CAR T cells can be produced in the process of inhibiting the progression of gastric cancer, and the role of tyrosine phosphatase SHP2 can be explored in this study, along with its molecular mechanisms. Methods: The research utilized subcutaneous tumor models in nude mice to assess gastric cancer progression. Protein expression was detected using Western blotting, while Q-PCR examined the expression levels of lncRNA SNHG18 and miR-211-5p in MGC-803 cells. The relationship between miR-211-5p and lncRNA SNHG18 can be analyzed by dual luciferase reporter genes. The migratory ability of MGC-803 cells was determined through wound healing and transwell experiments, and cell proliferation was evaluated using a CCK-8 assay.Results: SHP2 was found to inhibit the cytotoxic effects of CAR-T cells on MGC-803 cells, and it suppressed the expression of proteins related to the ROS/ JNK/NFAT4 signaling pathway in MGC-803 cells and the miR-211-5p/BRD4 axis in CAR-T cells. In addition, the proliferation, invasion and migration of MGC-803 cells were promoted, and the expression of miR-211-5p could be inhibited specifically by ncRNA SNHG18, as shown below: SHP2 in gastric cancer cells mediates the ROS/JNK/NFAT4 signaling pathway and induces lncRNA SNHG18, which, through the miR-211-5p/BRD4 axis in CAR-T cells, promotes gastric cancer growth and metastasis.