Objective: To compare the therapeutic effect of Shenmai injection (SM) and aminophylline (AP) on diaphragm fatigue in chronic obstructive pulmonary disease (COPD). Methods: Sixty four COPD patients with respiratory failure and diaphragm fatigue were randomly divided into 2 groups. The SM group (n=33) was treated with oxygen inhalation, anti infection agents, and SM injection (SM 40ml + 10% glucose 100ml). The AP group (n=31) was treated by the same comprehensive treatment but with AP 0.25g instead of SM. The initial time of diaphragm fatigue disappearance, 24 hrs maintaining effect and the arterial blood gas analysis were observed. Results: The effect in 30 min and maintaining effect in 24 hrs in SM group were better than those in AP group. In both groups, PaO 2 increased and PaCO 2 decreased. Conclusion:The therapeutic effect of SM on COPD patients with respiratory failure and diaphragm fatigue was better than those of AP. Method: Sixty four COPD patients with respiratory failure and diaphragm fatigue were randomly divided into 2 groups. Objective: To compare the therapeutic effect of Shenmai injection (SM) and aminophylline (AP) on diaphragm fatigue in chronic obstructive pulmonary disease (COPD). SM group (n=33) was treated with oxygen inhalation, anti infection agents, and SM injection (SM 40ml + 10% glucose 100ml). The AP group (n=31) was treated by the same comprehensive treatment but with AP 0.25g Instead of SM. The initial time of diaphragm fatigue disappearance, 24 hrs maintaining effect and the arterial blood gas analysis were observed. Results: The effect in 30 min and maintaining effect in 24 hrs in SM group were better than those in AP group. In Both groups, PaO 2 increased and PaCO 2 decreased. Conclusion: The therapeutic effect of SM on COPD patients with respiratory failure and membrane fatigue was better than those of AP.