Recent advances in highly efficient algorithms and high-performance computing allow us to build integrated design framework where the traditionally separate disciplinary models are coupled together, so as to improve the design optimization of hypersonic vehicles as integrated systems. Our particular interest in this paper is the potential approach to incorporating high-fidelity aerothermodynamic models in the hypersonic trajectory optimization problems. First, the necessity and motivation of considering high-fidelity aerodynamics are justified. Then, both the time-based and energy-based problem formulations for hypersonic trajectory optimization are introduced. Different from the conventional design approaches in the literature, two high-fidelity aerodynamic models are built and integrated in the trajectory optimization process. One is a panel method based on the modified Newtonian flow theory and Eckert’s reference enthalpy method, and the other is a CFD model based on the Reynolds-Averaged Navier-Stokes equations. A pseudospectral optimal control package is used to solve the considered problem, and preliminary results demonstrate the feasibility of the developed approach.