According to the power system voltage state of emergency, a reactive power voltage control partitioning based on grey correlation is proposed. Firstly, the sensitivity matrix is formed by the general Tellegen’s theorem, and then the reactive power voltage control region taking fault voltage node as the center is founded quickly. Secondly, the method of grey correlation is used to decide whether the divided region’s edge control nodes are remained or abandoned. The control nodes connected with the divided region are searched to calculate the grey correlation between every control node and the nodes which connect with it. According to the value of grey correlation to decide whether the control nodes are remained or abandoned. In this way, the reactive power voltage control partitioning is getting more right. IEEE-30 test system shows that the emergency reactive power region formed by the proposed method is simple, fast, and practical.