Abstract: Objective To explore the clinical features and survival of patients with advanced gastric cancer or gastroesophageal junctional cancer (GC/GEJC) treated by chemotherapy plus immunotherapy. Methods From May 2015 to May 2019,patients with advanced GC/GEJC who were treated in the department of oncology,the first medical center of Chinese PLA General Hospital were included in our study,with 37 patients treated with chemotherapy (fluorouracil/capecitabine/tegafur combined with platinum-or taxane-based drugs) as chemotherapy group,and another 34 patients treated with chemotherapy combined with immune checkpoint inhibitors (PD-1,Nivolumab or Pembrolizumab) as combination group.Clinical outcomes were observed and compared between the two groups. Results The progression-free survival (PFS) was 3.93 months (95% CI:1.56-6.30) in the combination group and 4.97 months (95% CI:3.36-6.58) in the chemotherapy group (P=0.242);and the overall survival (OS) was 14.37 months (95% CI:8.17-20.57) and 12.52 months (95% CI:9.82-15.22) (P=0.101);ORR was 23.5% and 18.9% (P=0.634),DCR was 79.4% and 75.7% (P=0.707).Mild (GradeⅠ-Ⅱ) adverse reactions were found in the two groups. Conclusion Chemotherapy combined with immunotherapy has certain clinical benefits for patients with advanced GC / GEJC,and further exploration of treatment strategies and screening of target population for immunotherapy are still needed.