To improve the precision of the aerodynamic coefficients of the projectiles during calculating trajectories and designing projectiles, the drag, lift, pitching moment, roll damping moment, Magnus force and moment of the projectiles are computed by solving N-S equations applying an implicit LU scheme, and considering an algebraic turbulence model and the boundary condition for rotating body surface. It is indicated that the aerodynamic coefficients of the rotating projectiles obtained by means of the numerical simulation are better than those previously obtained by means of the engineering estimate by the comparison of the computing results and the experimental results of the T388 shell, and by the ballistic calculations of a certain howitzer projectile using the aerodynamic coefficients obtained with this technique.