Ground effect dramatically improves the performance of the Wing-in-Ground (WIG)vehicles near the ground.However,making coordinate turnings in ground effect zone may raise complexity in flight control.The Angle of Attack (AOA) and height are believed to be important factors.To find the impact of these factors,three straight rectangular wings with different aspect ratios are simulated via CFD approach.The results show that in normal situations,the rolling moment tends to level the wing but less effective with the decreasing AOA and changes its direction when the AOA is less than a height dependent value.The yaw moment exhibits complex behavior because two different effects generate oppose moments.The rolling moment coefficient is more influenced by the ground if a wing has larger Aspect Ratio (AR) and works at low to medium AOA.The yawing coefficient is always more influenced if the wing has larger AR regardless AOAs.These findings can provide basic guidance for the design of control system and enable aircraft designers to reshape the crafts to avoid or utilize this effect.