Only a few investigations were based on limb bone density. This study evaluated the efficacy of soy isoflavone in the treatment of the principal menopausal disorders, limb bone density and the role of pathway. The research protocol involved the random subdivision of the enrolled sample into two groups of 40 women, who were to receive treatment for 6 months with isoflavone (90 mg/day) and with placebo. All of the patients were asked to fill in a questionnaire concerning their complaints. BMD of the radius and tibia were measured using quantitative ultrasound. Bone metabolism indexes calcium, phosphorus and alkaline phosphatase (ALP) were examined regularly. Serum cytokines interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) examined by ELISA. The results of the score of Kupperman table showed that the isoflavone can lead to a significant reduction in some of the disorders. Compared with placebo, the tibia bone density in isoflavone group increased obviously against the base value before trail. Isoflavone led to a stronger descent of the concentration of ALP and a decrease of IL-6 and TNF-α level than placebo. For climacteric women, soy isoflavone in the dose of 90 mg/day could improve some menopausal syndromes and was effective on increasing limb bone density, which maybe had the relationship with the levels of IL-6, TNF-α and ALP in serum.