OBJECTIVE： To evaluate therapeutic efficacy and safety of orlistat versus metformin in reducing body weight of overweight or obese patients， and to provide evidence-based reference. METHODS： Retrieved from PubMed， Embase， Ovid， Web of Science， Cochrane Library， Chinese Journal Full-text Database， Wanfang database and VIP， RCTs about orlistat alone or combined with metformin （trial group） versus metformin alone （control group） in reducing body weight， BMI and the incidence of ADR of overweight or obese patients were collected. Meta-analysis was performed by using Rev Man 5.3 statistical software after data extraction and quality evaluation with modified Jadad scale. RESULTS： A total of 9 RCTs were included， involving 502 patients. The results of Meta-analysis showed that， when orlistat combined with metformin， the reduction of BMI in trial group was significantly better than control group， with statistical significance [SMD＝－0.74， 95％CI （－1.22，－0.26），P＝0.002]. There was no statistical significance in the reduction of body weight [SMD＝－0.04，95％CI （－0.27， 0.20），P＝0.76] or the incidence of ADR [RR＝1.07，95％CI （0.68，1.68），P＝0.78] between 2 groups. CONCLUSIONS： Both orlistat and metformin can reduce body weight with good safety. Combined use of these two drugs can reduce body weight more significantly.