【Abstract】 Objective To investigate the diagnostic value of combined detection of serum carcinoembryonic antigen and carbohydrate antigen in gastric cancer peritoneal metastasis. Methods 68 patients with gastric cancer treated in Oncology Department of our hospital from June 2014 to June 2017 were divided into metastasis group (20 cases) and nonmetastasis group (48 cases), according to the pathological or cytological examination. The levels of carcinoembryonic antigen (CEA), carbohydrate antigen CA724, CA242, CA211, CA199 and CA125 were detected by automatic immunoassay analyzer before operation or chemotherapy. The serum level and positive rate of the two groups were compared. The diagnostic efficiencies of the single and combined detection of these tumor markers were evaluated through establishing Logistic regression model,drawing ROC curves and calculating the areas under the curve (AUC). Results The serum levels of CEA, CA724, CA242, CA211, CA199 and CA125 in the metastasis group were significantly higher than those in the non metastasis group, and the difference was statistically significant (P＜0.05). The positive rates of serum CA724, CA125 and CA211 in metastasis group were significantly higher than those in nonmetastasis group (P＜0.05), while no difference was found in the positive rate of the serum CEA, CA242, CA199 of the two groups (P＞0.05). The AUC of combined detection (Y1) of CA125, CA724 and CA211 or combined detection (Y2) of the all tumor markers was significantly greater than that of any single detection. Conclusion CA125 can be as a predictor for peritoneal metastasis of gastric cancer, and its detection in combination with CA724 and CA211 can provide effective information for clinical identification of gastric cancer peritoneal metastasis.