A numerical simulation method for controlling dynamic stall of rotor airfoils under unsteady freestream conditions using dual synthetic jet is established to address the dynamic stall issue of rotor blades during high-speed forward flight of helicopters. A moving-embedded grid method is employed to simulate the changes in freestream velocity and airfoil pitch by translating and rotating the airfoil. The effects of various synthetic jet parameters (momentum coefficient, jet frequency, jet location, and jet angle) on the control of dynamic stall under unsteady freestream velocity conditions are investigated for the NACA0015 airfoil at both high and low freestream velocities. The results show that increasing the momentum coefficient improves the control of the airfoil’s lift characteristics but weakens the control of drag. Increasing the jet frequency raises the oscillation frequency of the aerodynamic characteristics, with a slight improvement in lift control. The tangential jet angle (30°) requires a higher momentum coefficient for better control at high freestream velocities, but a lower momentum coefficient is sufficient for low freestream velocities. Furthermore, As a result of a suitable combination of jet parameters, the lift coefficient of the airfoil is increased by 61.93% and the drag coefficient is reduced by 71.03% at high freestream velocities; at low freestream velocities, the lift coefficient is increased by 43.76% and the drag coefficient is reduced by 20.14%.