Objective: To investigate the application value of combined detection of serum carcinoembryonic antigen (CEA) and carbohydrate antigen CA19-9, CA125, CA724, CA211 and CA242 in diagnosis of gastric cancer peritoneal metastasis. Methods: The values of tumor markers in 89 gastric cancer patients treated in the Affiliated Xinhua Hospital, School of Medicine, Shanghai Jiaotong University from December 2015 to December 2016 were collected. Of the patients, 17 cases had peritoneal metastasis (metastasis group) and 72 cases did not have peritoneal metastasis (non-metastasis group). 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 positive detection rates of CA125, CA211 and CA724 in metastasis group were significantly higher than those in non-metastasis group (all P<0.05), while the positive detection rates of the other three tumor markers showed no significant difference between the two groups (all P>0.05). In single detection, the AUC of CA125 for diagnosis of gastric cancer peritoneal metastasis was biggest, which was significantly different from the other five tumor markers (all P<0.05); the AUC of combined detection of CA125, CA724 and CA211 or combined detection of the six tumor markers was significantly greater than that of any single detection (all P<0.05), but the AUC showed no significant difference between them (0.964 vs. 0.949, P=0.866). Conclusion: CA125 can be as a predictor for peritoneal metastasis of gastric cancer, and its detection in combination with CA724, CA125 and CA211 can provide effective information for clinical identification of gastric cancer peritoneal metastasis, but has no significant value in combination with other tumor markers.