[Objective] Wind tunnel simulation tests of high-density polyethylene（HDPE） board fences with the same hole diameter but different opening directions were conducted in order to provide a theoretical basis for the better application and better effect of HDPE board sand-blocking fences. [Methods] Wind tunnel simulations compared wind speed profiles， aerodynamic parameters， flow field characteristics and windbreak efficiency between fences featuring holes oriented horizontally versus vertically. The analysis focused on the impact of hole orientation （horizontal vs. vertical） on windproof performance. [Results] Both fence types exhibited logarithmic wind speed distributions at -1 H （H = fence height of 23 cm） upwind and 9 H downwind （p<0.05）. The vertical hole configuration demonstrated superior profile stability， with higher aerodynamic roughness and greater friction speed than its horizontal counterpart. Flow field analysis revealed that the horizontal fence exhibited notable near-surface acceleration zones （from -1 H to 2 H）， and its deceleration zone split into two parts （1—5 H and 8—15 H） in response to increased wind speed. However， the vertical fence effectively regulated sand transport through controlled speed gradient attenuation， and its deceleration zone changed little with the increase in wind speed. In particular， the vertical fence’s deceleration zone maintained stable aerodynamic characteristics across the wind speed regimes. Windbreak efficiency progression showed three phases： a moderate improvement of 5.1%—8.4% （from -7 H to -1 H）， abrupt decline of 43.3%~55.6% （from -1 H to 1 H）， and a gradual increase in stability （43.3%—55.6%） post -1 H. At higher wind speeds， the windbreak efficiency of the vertical fence was 50.4% higher than that of the horizontal fence （p<0.05）. Notably， the efficiency of the horizontal fence decreased by 45.6% with increasing wind speed （p<0.05）， whereas the vertical fence maintained consistent performance （p>0.05）. [Conclusion] HDPE fence with vertically oriented holes demonstrated superior comprehensive wind speed reduction capacity， remarkable flow field stability， and maintained performance across variable wind conditions， indicating significant potential for large-scale application in sand control and desertification prevention engineering.