Abstract: Numerical simulation and twophase fluid flow theory were employed to calculate the characteristics of engine compressor with inlet water ingestion.Droplet model,loss and deviation model corrected by test data were used in the calculation.The investigation of water content,droplet size etc.,which would affect the compressor performance,shows that inlet water content and size of droplets have significant influence on compressor performance.In addition the results indicate that this method is effective and valuable in engineering application.