The technique of projectile deviation calculation plays a key role in identifying and assessing the accuracy of antiaircraft guns, and do the simulations can help improve the quality and save costs of testing and development. To improve the projectile deviation calculation accuracy and do the computer simulation more quickly and accurately, an algorithm based on the target model of uniform linear motion is proposed in the paper. The calculation process of the algorithm is described in detail. The computer simulation based on one kind antiaircraft gun is done, and the simulation results are analyzed. The results show that the algorithm is more accurate and do the simulation faster. What’s more, the simulation results of the algorithm can be used to assess the effect of shooting, and can be used to make judgments on the combat capability of antiaircraft guns, so it has certain practicability.