Abstract: A new flow control flap, spiral flap, was designed by gradually increasing the curvature radius based on Archimedes helix theory. The influence of the key control parameters such as the initial radius and alignment radius of the spiral flap on the upper surface jet deflection is studied. The control effect of the spiral flap is compared with that of the traditional basic flap, and the control mechanism of the two is analyzed. The results show that the maximum average thrust deflection angle of the spiral flap is about 20°. Compared with the basic flap, the spiral flap has larger average thrust deflection angle and higher thrust efficiency at large drop pressure ratio, which indicates that changing the curvature profile can promote the flow adhesion of the jet and improve the performance of the upper surface blowing system.