Abstract: In order to avoid irrational reactive power flow and voltage distribution,the coordinated voltage controlsystem integrated for regional,provincial and prefectural control centers in China Southern Power Grid is proposed.The reactive power and voltage operation and control characteristics of China Southern Power Grid are analyzed.The hierarchical architecture of coordinated voltage controlsystem integrated for regional,provincial and prefectural control centers is described.Some typical applications are emphasized,including the coordination between regional and provincial control centers,the coordination between provincial and prefectural control centers,the voltage control for substations considering the provincial coordinate constraints,the coordinated voltage control for the high voltage direct current（HVDC）neighboring grids,etc,the exchange data content and mode between regional,provincial and prefectural control centers are described.The coordinated voltage control system is currently in real time operation in China Southern Power Grid.