Abstract Background Osteoporosis (OP) is common in patients with chronic obstructive pulmonary disease (COPD). The relationship between OP and COPD has been primarily studied in male patients, and few reports are available in postmenopausal women. Objective The purpose of this study was to investigate the association between bone mineral density (BMD) and COPD in postmenopausal women. Methods This cross-sectional study included 133 clinically stable female ex-smokers with confirmed COPD, and 31 age-matched “ex-smoker” female controls. We analyzed groups according to their airway obstruction category. BMD was measured on dual-energy X-ray absorptiometry images of the left femoral neck. Results Patients with COPD had lower T-scores and higher prevalence of osteopenia/OP than the control group. In the COPD group, the airway obstruction category was significantly associated with the T-score after adjustment for confounders. Multivariate logistic regression analysis showed COPD was an independent marker for increased risk of osteopenia/OP in postmenopausal women. Conclusions COPD and airway obstruction category were strongly related to BMD. Postmenopausal women with COPD, especially those with severe airway obstruction, had a higher prevalence rate and a higher risk of osteopenia and OP than female controls without COPD.