Abstract: In order to elucidate the wake characteristics of horizontal axis wind turbine operating in uniform inflow, by using the shear stress transport turbulence model, a rotor of 33 kW two-blade horizontal axis wind turbine was simulated through solving the Reynolds time-averaged Navier-Stokes equations at different tip speed ratio. The results show that, in addition to the edge of the wake region, axial velocity deficit begin to remain the Gaussian self-similarity at a certain distance of downstream, and the greater the tip speed ratio is, the easier axial velocity deficit reach self-similarity state at downstream of wind turbine. Meanwhile, with the increase of the tip speed ratio, the wake expansion effect is more obvious and the tip vortices and root vortices break down early with the process of vortices propagate downstream. Within the range of two rotor diameters downstream of the turbine, the vorticity strength of tip vortices and root vortices decrease gradually with the increase of the distance from the wind turbine rotor, but the size of the vortex core is increasing. At the same axial position of wake region, the vorticity strength of tip vortex is always greater than that of the root vortex.