通过对蒸汽锅炉汽包水位产生扰动的主要因素及调节原理进行分析，结合工程实践，提出了基于PLC的锅炉串级三冲量给水控制系统，并介绍了数字PID控制算法在单片机上的实现，实践表明，该控制系统能较好地克服虚假水位现象，控制效果良好。-The main factors which affecting industrial boiler water level disturbing and control principle have been analyzed. Integrate with the practice,puts forward cascade three-impulse water-supply control system and introduces the implement of digital PID control formula based on SCM.The results of practice indicate that the system can overcome the ostensible water level and has a better control effect..