Abstract In recent years, with the rapid expansion of urban power grids, the automatic voltage control (AVC) system develops some new characteristics. Based on the technology of big data analysis and mining, this paper expounds an AVC system for urban power network with high load density based on the integrated dispatch and operation mode. This paper introduces several different application modes, and shows the operation characteristics of the multi-point distribution mode and the integrated control mode. The big data mining technology is used to discovering the hidden troubles and defects in AVC system. This paper also presents some other AVC key technologies such as security check of remote control, self-adaption analysis method and so on.