Abstract: The Crew Space Transportation System (CSTS) is a proposed next generation manned exploration vehicle which will transport crew both to the ISS in Low Earth Orbit, and to Low Lunar Orbit. In this paper, orthogonal numerical experiment with four factors and three levels was arranged, using the orthogonal experimental design method. The influence of geometric parameters on the aerodynamic characteristics was discussed, aiming at finding the configuration with the highest L/D value. After selecting the configuration, the trim L/D line was found out for the required L/D. The placement of the center of gravity on the trimline which affects the pitch static stability and the aerodynamic sensitivity to the placement was investigated for better aerodynamic perfermance.