This paper introduces a trajectory optimization method for powered aeroassisted orbital transfer vehicle (AOTV), which combines thrust and aerodynamic force to optimize the trajectory. The thrust adopts a fixed magnitude and adjustable pulse width form. By assuming the magnitude of the thrust is continuous, the Gauss pseudospectral method (GPM) is used to solve the trajectory optimization problem and generate the optimal trajectory that satisfies multiple constraint conditions. To obtain a fixed magnitude thrust form, the thrust from the first optimization result is converted into a thrust switch sequence using Pulse-Width Pulse-Frequency (PWPF) modulator, and the thrust analysis model based on the optimal trajectory is reconstructed. Ultimately, using the reconstructed thrust model as the known thrust, GPM is applied again to optimize the trajectory, determining the optimal angle of attack and bank angle. Taking the optimization design of the shortest time required for AOTV to reach the task point as an example for simulation analysis, the simulation results confirm the correctness and validity of the optimization scheme, indicating that the research method in this paper can be used for the optimal design of the flight trajectory of the powered AOTV.