Abstract: To improve both security and fall point precision of air guidance trajectory of a rocket assisted torpedo with a main engine of solid rocket, an approach to ensure the safest glide trajectory is proposed by solving the intersection set of design field of glide trajectory under different conditions and taking the relative distance between the glide trajectory and intersection set edge as a parameter. A guidance scheme adopting dynamic base trajectory during glide and variable separation point of torpedo and rocket is presented. The guidance system calculates guidance trajectory through programmed interpolation during the torpedo rocketing into the air, and corrects the trajectory towards the safest glide trajectory. The scatter scope of separation points of torpedo and rocket can be narrowed obviously when the height of separation point is adjusted with speed at the end of the trajectory. The results show that the security can be improved as the base trajectory is solved in the intersection set. Dynamic base trajectory may enhance the tolerance of trajectory error and target correction, which helps to overcome the interference of strong wind field.