Taking the research background of unmanned combat aerial vehicle (UCAV) chasing enemy at close range, a prescribed performance-based adaptive sliding mode maneuvering guidance law (PPASMGL) with energy boundary is designed. First, a prescribed performance function based on the energy-maneuverability boundary is designed. Then, the practical finite-time stable theory-based adaptive interference suppression sliding mode guidance law is derived to track line-of-sight (LOS) angle. Finally, a maneuvering situation with variable speed and acceleration was designed for numerical simulation verification. The results show that while the trajectory overshoot is reduced, the response time to the target maneuver is shortened and the proportion of positive specific excess power is increased.