In view of the heat flow, overload, and dynamic pressure constraint problems during the reentry process of the lift reentry vehicle, a calculation method of the reentry reachability region under multiple constraints is designed. Using the virtual target method, an optimal control model for the reentry reachability region is developed without the state inequality restrictions. A predictive correction method is designed based on the optimal control without process constraints, which converts state inequality constraints into control inequality constraints. The numerical simulation of the X-33 is completed. The results of the numerical simulation demonstrate that, in contrast to the conventional "soft constraint" method, which depends on the quasi-equilibrium glide conditions, the suggested method is capable of achieving “hard constraint,” meaning that all process constraints can still be strictly satisfied even in the event that the aircraft makes large maneuvers quickly.