The invention relates to a supporting and evaluating system for network voltage. The supporting and evaluating system comprises a measuring unit, wherein the measuring unit acquiring a network real-time data source to be transmitted to an energy management system; the energy management system is used for calculating and analyzing preparation data of a topology analysis module, a state analysis module, a load flow calculation module and a reactive optimization module; a voltage supporting and evaluating calculation module is used for calculating the voltage supporting conditions of corresponding nodes according to voltage supporting evaluation indexes on the basis of a network topological structure connected relation obtained from a network topological analysis result, network equipment structure parameters provided by the energy management system and network panoramic voltage state phase quantity obtained by PMU, load flow calculation or state estimation or reactive power optimization. The voltage supporting level of each load node in the network can be measured, and then the supporting weak nodes of network voltage is definite, the system is significant for network reactive compensation and configuration, and the system has good actual application prospects.