Abstract: Objective To observe the hemodynamic changes in patients with congenital heart disease accompanying pulmonary hypertension before and after iloprost inhalation. Methods Thirty-four patients with congenital heart disease（10 with atrial septal defect,19 with ventricular septal defect,2 with patent arterial duct,2 with ventricular septal defect accompanying patent arterial duct,and 1 with atrial septal defect accompanying ventricular septal defect） underwent right heart catheterization.Their hemodynamic changes were recorded after inhalation of oxygen and iloprost. Results The mean pulmonary arterial pressure and the total pulmonary resistance were significantly lower in the patients after oxygen and iloprost inhalation than before oxygen inhalation（（64.35±14.44）mmHg and（57.41±12.94）mmHg vs（74.53±12.48）mmHg,（958.03±355.83）dyn/（s·cm⁵） and（762.59±296.86）dyn/（s·cm⁵） vs（1 291.85±417.19）dyn/（s·cm⁵）,P＜0.01）.The cardiac index was significantly higher in the patients after oxygen and iloprost inhalation than before oxygen inhalation（（3.34±0.58）L/（min·m²） vs（3.07±0.58）L/（min·m²） and（2.43±0.44）L/（min·m²）,P＜0.01）,but no significant change was observed in their heart rate and blood pressure.The positive rate of oxygen inhalation was significantly lower than that of iloprost inhalation（64.71% vs 76.47%,P＜0.05）. Conclusion Iloprost inhalation can judge the pulmonary reactivity better than oxygen inhalation.