Ducted fans have been extensively used in Unmanned Aerial Vehicles (UAVs) for a variety of missions because of high efficiency, high safety and low noise. Wind, as a kind of typical meteorological condition, brings significant aerodynamic interference to the ducted fan, which seriously threatens flight stability and safety. In this work, the numerical simulation with the Unsteady Reynolds Averaged Navier-Stokes (URANS) method and the sliding mesh technique is performed to evaluate the steady wind effect. The results show that the wind will lead to serious unsteady effects in the flow field, and the thrust fluctuates at the blade passing frequency of 200 Hz. As the wind speed increases, the rotor thrust increases, the duct thrust decreases, and the total thrust changes little. Flow instability may occur when the wind speed exceeds 8 m/s. As the angle of low-speed wind increases, the rotor thrust changes little, the duct thrust increases, and the total thrust increases. In addition, we figure out that cases with the same crosswind ratio are similar in results, and increasing the rotating speed or fan radius is beneficial to performance improvement in wind. The findings are essential to the ducted fan design and UAV flight control design for stable and safe operations in wind conditions.