Objectives To evaluate the expression and clinical significance of COX-2 in gastric carcinoma. Methods Such databases as PubMed, CNKI, WanFang Data and VIP were searched for the studies on the association between COX-2 and gastric carcinoma from inception to January 2017. Two researchers independently screened literature, extracted data and evaluate the risk of bias of included studies. RevMan 5.3 software were used to analyze the data. Results Eleven case-control studies involving 1 366 patients were included. The results of meta-analysis showed that, there were significant differences of COX-2 expression in the following comparisons: gastric carcinoma vs. normal esophageal tissues (RR=1.69, 95%CI 1.39 to 2.06, P<0.000 01), with serosa invasivevs. without serosa invasive (RR=1.37, 95%CI 1.14 to 1.66, P=0.001), clinical stages Ⅰ-Ⅱ vs. clinical stages Ⅲ-Ⅳ (RR=0.78, 95%CI 0.69 to 0.90, P=0.000 3), as well as lymph node metastasis vs. non-lymph node metastasis (RR=1.48, 95%CI 1.34 to 1.63, P<0.000 01). While no significant difference was found between well/general differentiation group and poorly differentiation group (RR=0.84, 95%CI 0.51 to 1.38,P=0.48). Conclusion COX-2 expression is associated with depth of invasion, clinical stage and lymph node metastasis, which prompts that COX-2 may play an important role in the occurrence and development of gastric carcinoma. Due to limited quality and quantity of the included studies, more high quality studies are needed to verify above conclusion.