Objective To establish an animal model of obese polycystic ovary syndrome combined with insulin resistance ( PCOS-IR) using two different method with a high-fat diet, and to compare the changes in endocrine and metabolic characteristics. Methods Rats were randomly divided into a control group (ordinary feed and purified water), a letrozole group (intragastric administration of 1 mg / kg), and a human chorionic gonadotropin + insulin (HCG+INS) group (subcutaneous injections). The latter two groups were fed a high-fat diet and 5% glucose solution. Gram staining was used to observe two estrous cycles. On the 23rd and 30th day, ovarian and uterine wet weights were measured. Hematoxylin-eosin staining was used to observe ovarian histopathology. Fasting blood glucose (FBG), and blood levels of triglyceride (TG) and total cholesterol (TC) were measured by a biochemical analyzer. Serum levels of follicle stimulating hormone (FSH), luteinizing hormone ( LH), estradiol ( E2), total testosterone ( T), and inflammatory factors tumor necrosis factor-α (TNF-α) and interleukin-1β ( IL-1β) were measured by enzyme-linked immunosorbent assays. The homeostatic model assessment of insulin resistance (HOMA-IR) was calculated. Real-time fluorescence quantitative PCR was used to detect ovarian TNF-α and IL-1β mRNA levels. Results The letrozole and HCG+INS groups both had disordered estrous cycles compared with the control group, but the HCG+INS group had occasional ovulation. On the 23rd day, uterine weight and E2 levels were significantly reduced, and ovarian weight, INS, HOMA-IR, TG, and T levels were significantly increased in the letrozole group compared with controls. In the HCG+INS group, INS, HOMA-IR, TC, TG, and LH levels were significantly increased, and E2 levels were significantly reduced compared with controls. On the 30th day, the levels of FBG, INS, HOMA-IR, TG, FSH, LH, serum TNF-α and IL-1β, and ovarian TNF-α and IL-1β mRNA levels were significantly increased in the letrozole and HCG + INS groups versus the control group. The letrozole group exhibited anovulation, hyperandrogenism, and obesity, as well as more obvious pathological changes consistent with polycystic ovaries. Conclusions Both approaches successfully induced the PCOS-IR animal model. The changes in body weight, and endocrine and metabolic indexes of the letrozole model on the 30th day were more consistent with the pathological characteristics of obese PCOS-IR.