Abstract: This paper reported the methods and results of maximum transdiaphragmatic pressure (Pdi max) and diaphragm electromyography (EMGdi) in 16 patients with obstructive emphysema. A correlation analysis showed that Pdi max is negatively related to Paco₂ FRC%, and positively to VC, IG, FVC and MVV closely. Diaphragmatic fatigue was induced by inspiratory resistive loaded breathing with the parameters of 60% Pdi max and 5 minutes lasting. The influencial effecta and clinical value of diaphragm examination were discussed.