The invention discloses an integer programming based reactive power instruction optimal allocation method for a province dispatcher during automatic volume control (AVC) province and local coordinated control process. The method comprise the following steps of (1) using a reactive power target value of a gateway of a province dispatcher with regard to a main transformer of the gateway at a high-voltage side in a splitting operation condition, and allocating total reactive power target values issued from the province dispatcher to two main transformers of the gateway by a local dispatcher with regard to the main transformers of the gateways run in parallel at the high-voltage side and run at a medium-voltage side and a low-voltage side in splitting operation conditions; (2) traversing a switchable reactive power device set Cin of 110kV and 220kV substation sets ST only run at the high-voltage side in two sub-regions, and forming respective available reactive power device set; (3) sequencing serious degrees of reactive power residual substations; and (4) carrying out combination enumeration on a capacitor, and finally forming an optimal capacitor set. By the method, the adjustment target can be enabled to be achieved by minimum action frequencies within the shortest time during the process of province and local combined dispatching, and adjustment oscillation is prevented.