To enhance the controllability of the spin-stabilized projectile, this paper proposes a new projectile model. The model achieves spin reduction by installing a de-spinning wing in the aft control kit, which reduces the rotation speed from high to low. This maintains a stable rotation speed during subsequent flights, providing a favourable working environment for the measurement and actuation structures. The projectile’s aerodynamic design sets it apart from traditional spin-stabilized projectiles and displays unique aerodynamic characteristics. Numerical simulation methods were used to calculate the lift coefficient, drag coefficient, chamfered moment, and rolling moment at various Mach numbers. A seven-degree-of-freedom ballistic simulation with a de-spinning wing is established to delineate the de-spinning process and analyze the effects of the chamfered moment and rolling moment at different stages. The conclusion demonstrates that the design of the de-spinning wing proposed in this paper can effectively decrease the rotation speed of the aft control kit from 300 r/s to 10 r/s within 8 s and maintain it below 10 r/s in subsequent flights. This paper provides a basis for future research into the control and navigation of spin-stabilized projectile.