Abstract： Objective To investigate the effect of combivent and alpha-chymotrypsin inhalants on the improvement of lung function in patients with chronic obstructive pulmonary disease (COPD).Methods One hundred and fifty patients with COPD were ranked in the order of COPD severity and a comprehensive evaluation of age,smoking status and other complications which may have effects on lung function.According to the rank of the patients,they were classified into three groups (combivent,alpha-chymotrypsin and control groups) according to remainder after their ranking numbers were divided by three.Each patient was given treatment two times ( one in the morning and one in the afternoon) for 5 consecutive days.Lung function and blood gas were detected before first spray atomization and after last treatment.The parameters such as forced vital capacity (FVC),Forced expiratory volume in one second (FEV1％),arterial oxygen pressure (PaO2 ),arterial carbon dioxide partial pressure ( PaCO2 ),arterial oxygen saturation (SaO2 ) were compared.Results In the combivent group,the parameters before and after treatment were:FVC[(69 ±17)％,(74±15)％,t =-4.223,P＜0.O1],FEV1％ [(68±21)％,(71 ±20)％,t=-2.777,P=0.008],PaO2[(74±7),(76±6)mmHg,t=-11.201,P＜0.01],PaCO2[(40±3),(39±2)mm Hg,t=3.888,P＜0.01],SaO2[(94.4±1.7)％,(94.9±1.1)％,t=-4.452,P ＜0.01 ].In the alpha-chymotrypsin group,the parameters before and after treatment were:FVC[ (66 ±13)％,(70±14)％,t=-32.375,P=0.022],FEV1％ [(63±13)％,(66±15)％,t=-2.229,P=0.030],PaO2[(72±8),(76±6)mmHg,t=-18.763,P＜0.01],PaCO2[(40±3),(38±2)mmHg,t=6.137,P＜0.01],SaO2[(94.0±1.8)％,(95.0±1.3)％,t=-9.339,P＜0.001.Conclusion Combivent and alpha-chymotrypsin inhalants are both effective to improve the lung function of patients with COPD.