To investigate the effect of prophylactic ovariectomy on sex hormone level and bone mineral density in postmenopausal women. Methods From January 2019 to January 2021, 58 postmenopausal women who needed total hysterectomy for benign uterine diseases and selected preventive resection of bilateral fallopian tubes and ovaries in Mianyang Central Hospital were selected. The bone mineral density (BMD) of lumbar spine and the levels of serum sex hormones, including estradiol (E2), testosterone (t) Follicle stimulating hormone (FSH) and luteinizing hormone (LH) were measured before operation as their own control, and analyzed by menopause years. Results The bone mineral density of postmenopausal women showed a continuous downward trend one month, half a year and one year after preventive oophorectomy, and decreased by about 11.2% one year after operation. The serum T concentration of postmenopausal women after preventive oophorectomy showed a downward trend at 1 month after operation (P＜0.05), and then showed a continuous and slow upward trend. There was no significant difference between the serum concentration and that before operation at 1 year after operation. Conclusion Female postmenopausal ovaries still have endocrine function. If prophylactic bilateral oophorectomy is performed, serum T will decrease in a short time and bone mineral density loss will accelerate significantly