Because of the fixed orbit of the space station in inertia space, it is important to design the trans-lunar trajectory of the probe based on the space station assembly. In this paper, considering the kinematic law of the moon, an integrated mathematical model for trans-lunar trajectory design is established, and the constraint conditions are presented according to practical situations in engineering. Then the main problem for orbit design is to solve the orbit dynamics equation in some constraint conditions. Appropriate object function and constraint conditions are chosen, and the equation is solved by using genetic algorithm and SQP method. The parameters of trans-lunar trajectory are calculated by using numerical method. Finally, by a comparison with the data gained from STK, the results are validated.