A numerical simulation method for rotor active flap control (AFC) is proposed based on the computational fluid dynamics(CFD) technology. The Euler equation is used to increase the computational speed when the parameterized analysis of airfoil characteristics is satisfied. The motion of the trailing edge flap of the AFC rotor is controlled by the moving overlapped grid method. Firstly, numerical examples are given to verify the results. Then, the numerical simulation of the AFC rotor airfoil is carried out. Finally, the influence of the main parameters of the AFC rotor airfoil on the blade vortex is also discussed. Results show that the vortex generation rate increases with the increasing of tip Mach number and trailing edge oscillation frequency. The strength of vortex increases with the increasing of tip Mach number, trailing edge swing, and trailing edge chord length. However, increasing the distance between the trailing edge and the main blade gap can increase vortex strength only in a certain range.