We present a method to design trajectory for a Lunar satellite under certain constraints. The constrains are classified into two categories. Kinetic constraints deal with the relative configurations among Sun, Lunar, Earth spacecraft and tracking stations, while the dynamic constrains concern the orbit of the spacecraft. The models to compute the trajectory under precision requirement and a method to search for a standard trajectory satisfying the constraints are developed in this paper, and are applied to the designing for a potential Chinese Lunar mission. Other relevant issues of importance such as the accuracy assessment, tracking and real time orbit determination are under research and the general ideas are introduced in this paper.