Abstract: Since the snowboarding platform is similar to the bridge structure, windbreaks can also make a competition wind environment with low wind speed for the ski jump. The effect of the windbreak porosities on the windproof performance is analyzed by means of numerical calculation. The paper systemically analyzes the laws of vortex structure, dimensionless velocity, influence coefficient of wind environment and turbulence intensity varying with windbreak porosity. The results show that the windbreak can improve the wind field structure on the ski slope effectively, but it can also cause significant vertical velocity component on the jumping height of athlete, which will affect the fairness of the competition. The influence coefficient of wind environment over the ski slope first decrease and then increase with the increase of the porosity of windbreak. Windbreaks with the porosities of 10%~20% have the best effect on preventing crosswind, their windproof efficiency are about 79%~97%, which can also effectively reduce the vertical velocity component on the jumping height of athlete. However, the turbulence intensity will be increased significantly at the same time. The windbreaks with the porosities of 10%~20% are preferred considering that the snowboarding platform is insensitive to the effect of wind loads.