In this study, we investigated the effects of a Chinese herbal medicine formula xiao-gao-jiang-zhuo (XGJZ) in obese rats induced by a high-fat diet. Ten male rats in the normal group were fed with a standard diet. Another 50 male obese rats were induced by a 12-week high-fat diet feeding, and were randomly divided into five groups (n = 10 per group): the model group, the high-dose XGJZ group, the middle-dose XGJZ group, the low-dose XGJZ group, and the sibutramine group. After 14 weeks of treatment, body weight, abdominal fat, blood lipid and serum insulin level were measured, and the protein and gene expression of PTP1B in liver tissue was tested. Our data showed that the body weight of the high-dose and middle-dose groups and the sibutramine group had significant differences in comparison with the model group (p < 0.05), and all three dose groups had significantly reduced abdominal fat (p < 0.05). The triglyceride level of the three dose groups and the sibutramine group, and the total cholesterol level of the middle-dose group were all significantly reduced (p < 0.05). The serum insulin of the high-dose and middle-dose groups also decreased significantly (p < 0.05). The expression of hepatic PTP1B mRNA of the three dose groups decreased significantly in comparison with the model group (p < 0.05 or 0.01). The expression of hepatic PTP1B protein of the high-dose and middle-dose groups decreased significantly (p < 0.05). Our data suggested that XGJZ can modulate the body weight, abdominal fat and blood lipid in the obese rats, and this modulation might improve insulin resistance by inhibiting the PTP1B signal pathway.