In order to solve the problem of large error when the ammunition velocity is in transonic velocity and calculating accuracy of simple fire control method checked by firing table, the paper analyses the problem and proposes the improvement measures. This paper analyses the reasons of the problem from 2 aspects, including example and theory, and gives an effective method to check the accuracy of the simple fire control method with firing table when the single factor trajectory condition changes. The results show that this method can evaluate the accuracy of fire control calculation more accurately.