In order to study the windbreak effect of the bridge wind fences in the Xinjiang section of the Gobi area in northwest, based on the Fluent wind-sand two-phase flow unsteady model and the standard κ-ε turbulence model, the most representative 32 m box girder structure of Lanzhou-Xinjiang high-speed railway was selected, and the effects of different porosity of wind fences on the distribution of wind-sand flow field of high-speed railway bridges and wind fences were analyzed.The results show that by using a wind fences with a certain porosity, the windward air velocity can be reduced, the resistance on the flow field around the wind fences is applied, resulting in the loss of air flow, so as to shield the leeward side; the wind fences can block part of the incoming wind, but it will increase the resistance and torque on the bridge and reduce the wind resistance of the bridge; too low porosity of the wind grid is detrimental to the stability of the bridge, and too high porosity is not conducive to the safety of trains, a wind fences with a porosity of 20%~30% is preferred.