Taking the 5MW wind turbine of the National Renewable Energy Laboratory (NREL) as the research object, the theoretical analytical model of downburst combined with the IECKAI fluctuating wind spectrum method was used to construct the three-dimensional fluctuating wind field of downburst, and the influence of the horizontal maximum wind speed of downburst at different heights on the wake characteristics of wind turbine was calculated and analyzed. The results show that when the horizontal maximum wind speed height of downburst is located at the bottom of the wind turbine wind wheel sweeping surface, the influence on the wind turbine wake is minimal. The axial wake velocity deficit is the largest when the horizontal maximum wind speed height of downburst is located at 0.5R below the hub. The wake characteristics of wind turbines are similar when the horizontal maximum wind speed height of downburst is located at the center of the hub, the position 0.5R above the hub and at the top of the wind turbine wind wheel sweeping surface.