Generator reactive power reserve plays a key role in power system voltage stability and control.A generator reactive power reserve definition based on voltage control area is proposed，which considers both its availability and value to static voltage stability and quasi steady-state voltage control.The characteristics and selecting criteria of control variables are analyzed in detail.Then a model for optimizing generator reactive power reserve and voltage profile is formulated，and a successive regional optimization algorithm is proposed.The rationality of the definition of the generator reactive power reserve and control variable selecting criteria is validated by numerical results on a 3-bus system.The feasibility of the algorithm is demonstrated by results on IEEE 118 system，and the dispatch scheme has significantly enhanced the reactive power reserve，voltage stability margin，and voltage profile.The reduction of the high dimensional original optimization problem to several low dimensional regional sub-problems，which leads to high fault tolerance and computational efficiency，is applicable to generator reactive power reserve evaluation and optimization of large systems.