Abstract:The method to design lunar free-return trajectory and hybrid trajectory was studied. The sectional perturbational high precision dynamical model was established, then the search variables, target parameters and differential correction algorithm were designed, and a nominal free-return trajectory was searched out, which was validated and three-dimensionally simulated by STK. In addition, the error transfer was analyzed. The paper described a typical design procedure of hybrid trajectory which combines free-return trajectory and non-free-return trajectory, and simply analyzed the advantages and disadvantages of it. The method and conclusions in the paper can be applied to conceptual design of manned lunar landing mission and trajectory design of the later stage of China Lunar Exploration Program, as well as trajectory design of micro lunar probe launched together with other spacecrafts.