本文介绍了PLC 系统对自来水厂配水设备的自动控制。根据装置的特点和用户的使用情况，选用增量式PID 调节。并通过软件和硬件的合理配合，使系统实现软启、软停及恒压供水。关键词：PLC；自动控制；PID；恒压供水Abstract: The paper introduces the automatic control of PLC system to installation of distribution water in waterworks, in which PLC is used to select the of increment PID to regulate according to the feature of units and the usable situation from users. At the same time, supplying water under constant pressure will be realized through the rational cooperation of softwares and hardwares.Reywords: PLC; automatic control; PID; supplying water under constant pressure