Abstract: Objective To identify the related factors of bone mineral density reduction in postmenopausal women with early breast cancer 1 year after surgery. Methods The clinical data of 242 patients with early breast cancer of postmenopausal women in our hospital were collected and analyzed. Univariate and multivariate logistic regression model was used for analysis of related factors of bone mineral density reduction in postmenopausal women with breast cancer. Results Univariate logistic analysis on ten potential risk factors showed that age, BMI, Oral AI endocrine therapy, postmenopausal time and level of estradiol were signifi cant variables affecting bone mineral density reduction(P < 0.05). Multivariate logistic analysis showed that Oral AI endocrine therapy, long postmenopausal time and low level of estradiol were major risk factors( P < 0. 05). Conclusion Oral AI endocrine therapy, long postmenopausal time, low level of estradiol are major risk factors of bone mineral density reduction of postmenopausal women with early breast cancer. We should pay great attention to the patients with these risk factors and carry out appropriate treatment to decrease bone loss incidence.