Abstract: This paper introduces the overview of the intelligent water supply system for the greening of a water purification plant in Tianjin and the intelligent switching method of several kinds of water supply modes,and focuses on analyzing the application of PLC for intelligent switching of water supply modes under different water supply flows. By optimizing the PLC program,the intelligent management of water supply system for greening is realized. By using the characteristics of stable operation and accurate analysis of the automatic control system,it not only reduces the workload of operators,but also improves the reliability of system operation.

Key words: PLC, intelligent, automation control