To overcome the difficulty in intercepting large maneuvering targets， a trajectory planning method based on adaptive energy allocation is proposed for the boost phase interceptors. According to the generalized nominal effort miss guidance， the burnout parameters for each stage are optimized and the fire tables with different energies are established. Before launching， an energy-reserved fire table is used for trajectory planning， and some energy is reserved to cope with the unknown maneuvers of the target in the future. Once the target's maneuvers have been identified， a more energy-efficient fire table is selected to re-perform trajectory planning based on the remaining flight time of the interceptor in boost phase， so that the reserved energy could be gradually released. The simulation results show a significant improvement in the effectiveness of intercepting large maneuvering targets.