Based on characteristics of large landing angle, heavy quality, and low maneuverability of bunker bomb, Gauss pseudospectral method (GPM) was used for optimal trajectory with minimum overload, satisfying both path constraints and terminal constraints. Global interpolation polynomial was used to transform nonlinear equation into discrete algebraic constraint equation so as to transform complicated nonlinear optimal control problem into nonlinear programming problem (NLP). Our numerical results show that optimal trajectory based on GPM has uniform and minimumoverload and performs better in this task, which reflects effectiveness and application potential of design.