Aiming at the problems such as the difficulty in optimizing morphing and the contradiction of multiple design objectives，the multi-objective approximate optimization for the boost-glide morphing flight vehicle trajectory scheme is studied.First，the optimization framework of an all-course trajectory scheme for boost-glide morphing flight vehicles is proposed，and the control parameters and trajectory scheme parameters are optimized through the inner and outer layers，respectively.Then，a multi-objective optimization model is formulated for the trajectory scheme that optimizes a target with the minimum takeoff mass and the maximum flight range.In the trajectory modeling，the boost stage trajectory model is constructed based on the Newton iteration method，and the optimal morphing model of reentry glide stage trajectory is established based on the pseudo-spectral method.Furthermore，a multi-objective approximate constrained optimization method based on differential evolution （MACO-DE） is proposed to optimize the boost-glide morphing flight vehicle trajectory scheme.Compared with the initial scheme，the take-off mass can be reduced by 3.81% at the same flight range，and the flight range can be improved by 6.62% at the same take-off mass，which demonstrates the reasonability of the all-course trajectory scheme and the effectiveness of the MACO-DE.