Mathematical model and characteristic analysis of return trajectory for lunar probe were studied. Firstly, mathematical model of return trajectory was established in 3D space; then some important characteristics were obtained from simulation analysis, especially those characteristics of trajectory escapes from lunar sphere of influence on longitude 80°E costing the least energy; at last an example with a preliminary trajectory and a precise trajectory was proposed, which proves that this analytical method is able to provide initial value for precise design，and the characteristics can guide the actual design.