Background: PD-L1/PD-1 pathway has become an important target in tumor immunotherapy. However, the prognostic value of PD-L1/PD-1 for gastric cancer (GC) remains controversial due to the complexity of immune response. Therefore, comprehensive evaluation of PD-L1/PD-1 expression and CD8⁺T cells is necessary and superior to one factor in predicting survival. Methods: 166 patients with stage II-III GC were enrolled. Expression of PD-L1, PD-1, and CD8 protein in tumor tissues was examined by IHC staining, and their association with patient’s survival was analyzed by Kaplan-Meier method. Immunoscore classification was constructed using a scoring system, which was based on hazard ratios in a Cox proportional hazard analysis. Results: Expression of PD-L1 was found in 22.29% of immune cells (IC) and 38.55% of tumor cells (TC), while expression of PD-1 was found in 31.33% of IC. CD8^High was detected in 41.57% patients. PD-L1⁺ and PD-1⁺ IC were both correlated with worse overall survival (OS) (P=0.0009 and P=0.0004, respectively). In contrast, TC PD-L1⁺ was associated with better clinical outcomes, including Borrmann classification 0-1, lower AJCC stage, CD8^High infiltration and better OS (P<0.05). Furthermore, IC PD-L1, IC PD-1, CD8, and TC PD-L1 had independent prognostic significance after TNM stage adjustment, and we built an immunoscore system based on these immune factors. Patients with same stage could be further categorized into low-/median-/high-risk subgroups according to their immunoscores. Conclusions: Immunoscore based on comprehensive evaluation of PD-L1/PD-1 and CD8⁺ T cells can separate GC patients with same stage into different risk subgroups, and might provide suggestion for immunotherapy options in GC.