Glutathione S-transferase M1 (GSTM1) polymorphism has been proven to be associated with risks of several cancers. However, previous studies on the association between GSTM1 polymorphism and colorectal cancer risk in Chinese population reported controversial results. We performed a meta-analysis of 13 studies which were identified through the literature search in PubMed and Wanfang databases. The strength of the association between GSTM1 polymorphism and colorectal cancer risk was measured by odds ratio (OR) with corresponding 95% confidence interval (95% CI). Overall, GSTM1 null mutation was significantly associated with a risk of colorectal cancer in Chinese population (OR = 1.37, 95% CI 1.12 to 1.68, P = 0.002). Sensitivity analyses by omitting those studies in turns did not materially alter the overall pooled ORs. The cumulative meta-analyses further showed a trend of an obvious association between GSTM1 null mutation and risk of colorectal cancer in Chinese population as information accumulated by year. The findings from our meta-analysis suggest that GSTM1 null mutation is significantly associated with a risk of colorectal cancer in Chinese population.