In the 1980s, a large number of advanced foreign automation control technologies and equipment were introduced into my country, accelerating the automation process of water plants, improving production reliability and safety, achieving high-quality, low-consumption, and high-efficiency water supply, and obtaining good economic and social benefits. Water treatment is a crucial part of the water plant's water supply system. After the raw water enters the water plant, coagulant PAC, flocculant PAM, and primary chlorination are added to the raw water pipeline. The water is then mixed in a static pipeline mixer and enters a micro-flocculation filter. After reaction filtration, the mixed water is pressurized by a secondary pump station and enters the water supply network. The entire water plant's control system employs three methods based on priority: remote control from the monitoring center, local PLC control, and manual control of local equipment. The water plant's automated monitoring system uses a combination of GPRS and Ethernet communication, consisting of a monitoring center and five PLC control stations. The water plant's automated control system uses Hollysys' HOLLiAS LM series PLCs as the control unit, and each control station is configured according to its different input and output point requirements. The PLC control system for the pressure measurement station uses a 40-point CPU module LM3109 and a 4-channel analog input module LM3310 to periodically send the collected water network end pressure values ​​to the monitoring center. The monitoring center adjusts the outlet pressure setpoint of the secondary pumping station based on the uploaded pressure values ​​to achieve constant pressure water supply. The PLC control system for the regulating valve control station uses a 40-point CPU module LM3109, a 4-channel analog input module LM3310, and a 2-channel analog output module LM3320 to collect the status and data signals of the water intake motor, electric butterfly valve, and field instruments. It then sends control signals to these devices and automatically adjusts the motor operating frequency and the opening degree of the electric regulating butterfly valve through a pre-installed PID control program. The PLC control system for the chemical dosing and chlorination station utilizes a 40-point CPU module (LM3109), an Ethernet module (LM3403), an analog output module (LM3320), and four analog input modules (LM3310). This system collects status and data signals from field equipment and instruments in the chemical dosing and chlorination station and filter tanks, and sends control signals to them to achieve automatic operation control. The water plant automation control system based on the HOLLiAS LM series PLC achieves intelligent control, demonstrating stable performance, high reliability, and excellent field operation results.