〔Abstract〕 Abstract Objective To analyze the current status of anti-PD-1 combined with chemotherapy in advanced gastric cancer. Methods The clinical data of 120 patients with advanced gastric cancer treated with chemotherapy or anti - PD-1 plus chemotherapy were retrospectively analyzed . The efficacy [ measures include objective response rate (ORR) , disease control rate (DCR) , and progression-free survival( PFS) ] and the occurrence of adverse reac- tions in patients was monitored . Univariate and multivariate COX were used to analyze the relationship between clinicopathologic data (including age , gender , BMI , differentiation degree , and related hematological indexes) , specific treatment conditions and PFS , and to analyze the influence of treatment plan and line number on the cura- tive effect. Results The PFS of chemotherapy plus immunotherapy was significantly better than that of chemothera- py alone (P < 0. 05) , and the median PFS of the two was 7. 17 months (95% CI , 5 . 85 - 8. 49) and 5 . 33 months (95% CI , 3 . 96 - 5 . 70) , respectively . In the combination group , the overall ORR was 27. 5% and DCR was 94. 8% . In the chemotherapy group alone , the overall ORR was 9. 7% and DCR was 69. 4% . In the chemotherapy plus anti-PD-1 group , a high prognostic nutritional index (PNI) level also provided superior PFS in patients with a 47% reduction in the risk of progression versus a low PNI level [ HR 0. 53 (95% CI 0. 30 - 0. 96) ; P < 0. 05] . The median PFS was 7. 47 months (95% CI 5 . 83 - 9. 11) with a high PNI level versus 6. 00 months (95% CI 4. 45 - 7. 55) with a low PNI level . The overall incidence of adverse reactions of chemotherapy combined with anti-PD - 1 was slightly higher than that of chemotherapy alone , and the incidence of adverse reactions of grade 3 - 4 was similar , within a controllable range , and could be improved after clinical treatment. Conclusion The efficacy of anti-PD-1 combined with chemotherapy in patients with advanced gastric cancer is better than that of chemotherapy , and the adverse reactions are controllable . In the chemotherapy plus anti-PD-1 group , patients with high PNI levels achieved a higher PFS .