In this article, based on a rocket with high fineness ratio, its aerodynamic data was obtained with numerical simulation technology based N-S equations, and the aerodynamic characteristic in large range of altitude and Mach number from 0.6 to 5.0 was investigated. The research shows that when altitude is below 30 km, aerodynamic coefficients take a little change as altitude increases; But when it is above 30 km, and up to 50km and 80km, drag coefficient and lift coefficient increase greatly and pressure center moves ahead markedly, especially change greater when Mach number is lower. The designed ballistic trajectory based on the computational data accords with outfield flight test's results, which furthermore validates the computational method's reliability.