Based on idle and engine driving of a military transport aircraft equipped with a large bypass ratio turbofan engine in unpaved runway ground, a full⁃scale three⁃dimensional simulation model was established, By means of numerical simulation, the ground vortex distortion flow characteristics under different wind speed, wind direction and running speed were studied.The result showed that the ground vortex intensity first increased and then decreased under the 270 degree crosswind condition.The ground vortex intensity was maximal under wind speed range from 2 m/s to 4 m/s.The ground vortex disappeared when wind speed was more than 6 m/s.The ground vortex intensity was maximal and it had strongest suction capacity to foreign objects at 210 degree wind direction under the wind speed of 3 m/s.Also it had greatest influence on the inlet's outlet flow field.The ground vortex intensity and scope was weak under the condition of aircraft running compared with stationary, headwind. © 2021, Editorial Department of Journal of Aerospace Power. All right reserved.