The bidirectional interaction based coordinated voltage control mode for hierarchical electrical power control centers has broad application prospects. Provincial and prefectural control centers each provide operation information to the coordinator， in the form of coordinated constraints（including ability and expectation constraints）. Methods of generating the coordinated constraints are proposed. Optimization models are created for the provincial control center and the prefectural control center respectively based on the online adaptive control zone division results and online topological partition results， respectively. By real-time online solving the above-mentioned optimization models， the coordinating constraints are obtained. The global power flow method is adopted for a transmission and distribution combined test case simulation to verify the methods proposed， which has already been put into practical application in Jiangsu power grid in early 2009.