Abstract: It will improve the penetration performance for boost-glide vehicles by passing the radial zone quickly. How to describe the radial zone is a problem that must be solved in trajectory design. Based on the common multi-constraints trajectory design methods, the constraint of the radial no-fly zone is transformed to the threat coefficient constraint along the trajectory integral according to the radar equation. The cost function is given based on the integral of threat coefficient. The hp-adaptive Radau pseudo-spectral method is used to solve this optimization problem. A minimum threat trajectory satisfying process constraints and exposed to radial zone minimum is achieved. The threat model and this method are both proved to be right through comparing and analyzing the simulation results. The aim to improve the penetration performance is achieved.