Abstract: With the theoretical basis of aerodynamics, using fluid dynamics software (Fluent), simulated examination has been performed to analyze near-surface air currents, wind speed profile and windbreak performance of sand-bag barrier with different sizes. The results show that, below the surface of 0.5m height, the changes of wind profile of monitored section are consistent, with little difference, but the wind speed decreases between 0.5~2.0m height. There are clearly three partitions of the near-surface air: accelerated upwards area, low-speed sink area and low-speed recirculation zone. They are located in front of the sand barrier protection projects, above the top of the protection zone and inside the barrier, respectively. In low-speed recirculation zone, there exist two horizontal axis eddy current and the velocity at eddy center is minimum. In addition, it can be seen that 0.5m height is a critical point to distinguish factors of affecting wind speed. In the range of 0~0.5m, the height of sand barrier is the main factor of wind speed, while in the range of 0.5~2.0m, the size of sand barrier is the main factor. Considering comprehensively the above factors, it is realized that the sand-bag barrier with 2m×2m size has the most remarkable protective effect.