Objective：To investigate the changes of serum testosterone levels of elderly male chronic obstructive pulmonary disease （COPD） patients complicated with osteoporosis and its correlation with the severity of the disease. Methods：Totally 117 COPD patients and 40 non-COPD patients who were admitted to hospital from January 2015 to December 2015 were rolled into this study. According to the bone mineral density（BMD） and severity of illness，the patients were divided into different groups. The serum levels of testos－terone were compared. And the correlation of serum testosterone with the index of the severity was analyzed. Results：The serum testosterone level in COPD patients was significantly lower than that of non-COPD patients（P<0.05）. In the COPD patients，the serum testosterone level in osteoporosis group was significantly lower than that of normal bone mass group and low bone mass group，and that of low bone mass group was significantly lower than normal bone mass group（P<0.05）. With the aggravation of COPD，the serum testosterone level decreased significantly（P<0.05）. The serum testosterone level was positively correlated with FEV1/FVC（r=-0.267，P=0.011），FEV1% Pre（r=-0.291，P=0.009），and negatively correlated with smoking index（r=0.405，P=0.005），BMI（r=-0.304，P=0.006），CAT score（r=-0.583，P=0.000），lumbar spine BMD（r=-0.611，P=0.000） and femoral neck BMD（r=-0.382，P=0.002）. Conclusion：The serum testosterone level is significantly de－creased in COPD patients complicated with osteoporosis and is positively correlated with the severity of the disease. Detection of testosterone levels would help to the assessment of the sever－ity of disease.