In this study, we collected 488 gastric cancer tissues and 430 paired adjacent tissues to explore the difference in CD3D expression between tumor tissues and paracancerous tissues, as well as the correlation between the expression of CD3D and clinical information, prognosis, tumor-infiltrating lymph nodes (CD3+ T cells, CD4+ T cells and CD8+ T cells) and PD-L1. This evidence concerns the gene CD8A and gastric cancer.