A comparative study of performance characteristics in a gas turbine compressor before and after water injection into the air is carried out to explore the relationships between the transient characteristic and mist injection. The Eulerian-Lagrangian particle tracking method is used for solving a process of phase transition cooling of water/air coupling, and the fast Fourier transform (FFT) is adopted to analyze the frequency attributions of fluctuating quantities with time-dependent including total pressure ratio, total temperature ratio, and efficiency. Results show, after mist injection into the compressor, droplet evaporation phase change leads to a higher characteristic fluctuation in the low-frequency region. The sensitivity of efficiency fluctuation is easily affected by the mist injection by comparing with the dry air condition. Within the mist conditions of 1-5 mu m droplet sizes and 0.5-5% water/air ratios, the fluctuation of pressure in the compressor reaches a peak in small mist particle and low water/air ratio, resulting in a greater total pressure ratio. The temperature fluctuation gets the minimum in small droplet diameter and large water/air ratio, leading to a lower total temperature ratio. The fluctuation intensity of total pressure ratio, total temperature ratio and efficiency of compressor are increased to 3 times, reduced to 7/9 times and dropped to 3/5 times as water/air ratio increases from 0.5% to 5%, respectively; then, the fluctuation strength correspondingly increases 2 times, decreases 3/4 times and descends 6/7 times with the increase of droplet sizes from 1 gm to 9 Thus, the fluctuation caused by low water/air ratio is higher than the small droplet diameter. Furthermore, efficiency fluctuation gets a minimum in small droplet size and appropriate water/air ratio. (C) 2019 Elsevier Ltd. All rights reserved.