Abstract: In this paper, the application of a kind of rotary double slotted flap in the light aircraft is introduced, and the aerodynamic characteristics through the wind tunnel test were studied. The research results show that in normal flight speed range, the double slotted flap has less drag, high efficiency on lift Increment, pitching moment caused by the flap down changes a little, the aircraft integral performance is stable and high-lift performance is better. This paper emphasizes studies on the double slotted flaps at different wind speeds and different angles, the aerodynamic characteristics and its change rule.