In view of the solid rocket with multi-constraints and lower trajectory, improvement was implemented for traditional energy management. The improvement includes addition of an integral process based on the standard flight program. Besides, the improvement deducts expense of apparent velocity resulting from pneumatic power according to the character of lower trajectory, and the new method of calculating gross apparent velocity module has been introduced based on multi-constraints. Simulation results show that improved method can not only boost energy management efficiency, but also reduce velocity error, and validate practical value used in lower trajectory flight test.