针对登月舱上升段轨迹优化问题，建立上升舱动力学模型，用无量纲技术建立最优控制模型；以燃料消耗最优为指标，利用Pontrjagin极小值原理，将问题转化为时间自由的两点边值问题(TPBVP)。采用一种基于初值猜测方法和向前扫描法求解TPBVP，得到最优上升轨迹。仿真结果表明：此方法收敛速度快、可靠性高，为月面返回实际应用提供一定的参考。-According to the problem of trajectory optimization for the lunar module in ascent stage, firstly, the dynamical model of the module is established, as well as the non-dimensional optimal control-oriented model, secondly, to realize the minimal fuel consumption, the optimal problem is converted into a time free Two-Point Boundary Value Problem (TPBVP) based on the Pontrjagin’s minimal principle, finally, TPBVP is solved and the optimal trajectory is obtained using an initial value hypothesizing method along with the Forward Sweep Algorithm. The simulation results show that this method has advantages of rapid convergence velocity and high reliability, and can provide reference for the practical application of the module returning from moon