Abstract: Objective The aim of this meta analysis is to assess pharmacological effect of Sitagliptin in the treatment of type 2 diabetes mellitus. Methods Databases including The Cochrane Library（Issue 3, 2014）, CNKI, CBM, WanFang data, VIP, Elsevier-ScienceDirect, Oxford Journal, BMJ, PubMed, EMBASE, EBM and so on were electronically searched to collect the random controlled trials about the pharmacological effect of Sitagliptin, with the retrieval time from January 2006 to October 2014, and meta-analysis was performed. Result In all, 9 studies involving 3 284 participants were included. The results of meta-analysis showed that: Compared with placebo, Sitagliptin caused slight weight gain, the difference has no statistical significance WMD=0.26, 95%CI（-0.10,0.62）, P=0.16; Sitagliptin increased the function of insulin β cell compared with placebo, and the difference has statistical significanceWMD=11.02, 95%CI（7.96, 14.09）, P<0.000 01; there was also no statistically significant difference in the risk of gastrointestinal adverse event with Sitagliptin, compared to placebo RR=0.95, 95%CI（0.69,1.29）, P=0.73. Conclusion For the patients of type 2 diabetes mellitus, Sitagliptin can increase the function of beta cell of islet,it also has no obvious weight gain,and it has no obvious gastrointestinal reaction,so it can provide a new reasonable choice for the patients of type 2 diabetes mellitus.