Abstract: Using a row-to-row two-dimension nonlinear model,rotating stall parameters in a single rotor compressor are simulated, and compared well with the experimental data. The effects of inlet circumferential static distortion on the rotating stall in an one-stage compressor are investigated. Results show that there are no dramatic differences in stall parameters, whether the inlet flow is uniform or distorted. However, due to the interactions of inlet distortion, when stall occurs, the compressor displays not only a circumferential disturbance mode (stall wave), but also an axial disturbance mode (surge wave). Their coupling is an important factor for compressors' instability.