Introducing an energy consumption optimization strategy in quadrotor UAV trajectory planning to extend its flight longevity can significantly improve its practicality and economy.To this end, this paper proposes an energy-optimized trajectory planning method based on the Segmented Gaussian Pseudospectral Method (SGPM).Firstly, a comprehensive kinematics-energy consumption model of a quadrotor UAV is constructed, which can quantitatively describe the coupling relationship between UAV kinematics and energy consumption.Secondly, based on this model, the trajectory planning problem considering energy consumption optimization is transformed into a continuous time optimization problem with constraints.Finally, SGPM is designed to obtain the optimized trajectory, in which the sliding selection of optimization sub-intervals effectively reduces the computation time in complicated flight missions with a large number of waypoints, and at the same time improves the smoothness of the trajectory and the accuracy of waypoint tracking.The simulation and experimental results show that:1) Compared with the conventional fixed-waypoint flight, the proposed method can significantly reduce the flight energy consumption;and 2) Compared with the commonly-used optimization algorithms, the proposed algorithm ensures the optimization effect of energy consumption with shorter computation time and higher waypoint tracking accuracy.