The invention relates to a coordinated control method employing composite coordination gateways in provincial and regional coordinated voltage control and belongs to the technical field of automatic voltage control in a power system. The method comprises the following steps of: establishing corresponding composite coordination gateways in provincial and regional dispatching, and calculating and transmitting total active and reactive power and total reactive power upper and lower limits of the composite coordination gateways in real time; taking the total active and reactive power of each composite coordination gateway transmitted by regional dispatching as the current tide measurement of an equivalent generator by using provincial dispatching, taking the total reactive power upper and lower limits of each composite coordination gateway transmitted by the regional dispatching as reactive power adjustable ranges of the equivalent generator, performing unified global reactive power voltage optimized calculation, giving a reactive power coordinated target value of the equivalent generator corresponding to each composite coordination gateway, and using the reactive power coordinated target value as a coordinated control target of the composite coordination gateway; and taking reactive power coordinated constraint upper and lower limits of each composite coordination gateway as total reactive power constraint conditions of all equipment objects in the composite coordination gateway so as to realize provincial and regional coordinated voltage control.