Abstract: In order to meet the requirements of automatic control and electricity management of the drainage system of Xiaohezui Coal Mine, a set of mine main drainage monitoring system is designed and constructed. The principle of monitoring system based on PLC controller is introduced. From the main equipment composition, data structure, control algorithm flow and other aspects, this paper analyzes in detail the problems needing attention in the design and construction of the main drainage monitoring system, as well as the basic principles. In this paper, the problem of electric peak filling valley is analyzed, and the solution is provided and implemented.