Aerodynamic characteristics for a large civil aircraft are experimentally investigated at FL-9 low speed pressurized wind tunnel, focusing on the effect of Reynolds Number. The flow Mach number of 0. 2 and the pressure range of 1~4 atmospheric pressure are adopted in this test. The Reynolds number based on the model mean aerodynamic chord and free-stream velocity is from 2.9×106 to 11×106. Longitudinal aerodynamic characteristics of the wing are mainly analyzed. The experimental results show that the lift curve gradient, the maximum lift coefficient and the stalling angle of attack are all affected by Reynolds Number . Compared to the high lift configurations, the effect of Reynolds number on cruise configuration is more obvious.