The paper presents a numerical investigation of inlet distortion effects on the performance of a whole compressor. The compressor system consists of three and a half stages: a fan stage, an axial stage, a mixed-flow stage and an outlet guide vane. There are two bypasses after the fan stator. The following two and a half stages are in the core flow. The inlet distortion is generated by blocking part of the upstream inlet duct using a plate. The inlet distortion breaks up the original axisymmetric flow feature, thus a whole annulus computational domain has to be employed throughout the numerical unsteady analyses. The commercial GPU-based software of Turbostream is used to conduct all the analyses on several GPU workstations. The purpose of the numerical analysis is to understand how the inlet distortion propagates within this compressor and how the performance of each stage and the whole compressor is affected by the inlet distortion qualitatively and quantitatively. To achieve this goal, two separate numerical analyses have been performed for the compressor with and without inlet distortion at an interested operation point. For these two simulations, we do DFT analysis for the total pressure distribution at three spans of several different axial positions, such as the inlet and outlet of each stage, to get the spatial harmonic characteristic of each stage. The finding provides the insight needed to redesign the relevant stage to increase the surge margin.