In order to research engineering calculation accuracy of projectiles' exterior ballistic data, aerodynamic characteristics of some fin-stabilized projectile were simulated by FLUENT and the zero-lift drag coefficients of the projectile were acquired. They were piecewise fit by OriginLab to acquire the algebraic expression of the drag coefficient fitting curve, which was put in the exterior ballistic centroid movement differential equation for exterior ballistic data calculation. The result of method above was compared with that of classic coefficient of projectile form method. The error between data of trajectory was within 4.61% and the error between the whole exterior ballistic data acquired by both methods above was within 6.65%. The results indicate that even if the drag coefficient algebraic expression of the whole exterior ballistic could be acquired, the classic coefficient of projectile form method can also be used to calculate the exterior ballistic data of fin-stabilized projectiles in engineering application.