Water injection exerts an obvious influence on the performance of compressors during wet compression. Wet compression was numerically simulated using a single-stage axial compressor to study the motion of water droplets in a compressor. Results showed that water droplets in a compressor are mainly controlled by drag forces and that the Reynolds and Weber numbers of these droplets are low. Water droplets are most likely to break up in a model of vibrational breakup, and the break-up phenomenon mainly occurs around the leading edge of rotor blades. Some water droplets impact the blade during wet compression. Impingement of water droplets on the blade not only influences the motion and breakup of water droplets but also increases the load on the blade. The mass and heat transfer effects generated by smaller water droplets are better than those produced by larger ones, and the intensity of turbulent fluctuation is weaker, leading to lower viscosity loss. Considering the evaporation cooling, resistance loss, and impact effects produced by water droplets, small droplets and the proper amount of water injection should be chosen to minimize negative effects during wet compression. © 2017, Editorial Department of Journal of HEU. All right reserved.