Investigated the effects of onion peel extracts on weight reduction in obesity rats. The experiment adopted the nutritional obesity model, and selected the tea polyphenol (TP) as a positive control and fed with high-fat diet added 0.57% of tea polyphenol and 1.33% of onion peel extracts. Research studied the influence of onion peel extracts on body weights, Lee’s indexes, food intake and food utilization rate of the rats, and further evaluated weight-reducing capacity of onion peel extracts according to above parameters. The results showed that onion peel extracts could decrease the body weight significantly by restraining fat cell dilated and decreasing fat accumulation.