This paper proposes a novel cooperative strategy for the submunition to intercept the target which has a significant speed advantage. Making adjustment to the boundary of the maneuverability of the target, a more practical reachable set is applied to analyze the nonlinear engagement between the missiles and the target. Based on the reachability analysis, analyze the challenges of intercepting the target with submunition and divide the areas of responsibility among the missiles after the submunition’s separation. The place-holding phase is introduced into the guidance strategy design to address the challenges proposed before. Simulation experiments focus on the most challenging situation where the target moves along the boundary. Simulation results are given to confirm the effectiveness of the guidance strategy.