Abstract on-line control of coal flow is an important link. And It becomes a deserve research of topic. that how to guarantee the credibility of equipments operation , reduce the operational person and improve the economic performance, Programmable Logic Controller(PLC) is a kind of universal industrial control apparatus which is developed rapidly and used widely in recent years, taking microprocessor as its core , integrating microcomputer technology ,automation technology and communication technology. It is applied very diffusely in varied field of industrial control with the characteristics such as all-around functions. Flexible application, well reliability, high ratio of capability and price and maintenance and so on, having become a robust tool to realize automation. This paper takes SIEMENS S7-200 PLC as designing the some large boiler provide warm losing the coal control electricity system.The system can work reliably with property of easy operation and maintenance. The safety locks protection control function:In the system of losing the coal electrical engineering have the strict control in moving and stopping, each other has the homologous lock interaction relation, being start some set to lose the coal equipments, from that equipments below process of end lose the coal equipments start heading up pursue class start, then can make finally that set equipments start;When the stop some set loses the coal equipments or some set equipmentses to break down, from that equipments up the source head of the process starts get down for the coal equipments to pursue the class to park the car, then can make that set equipments stop finally.Thus, guaranteed the normal movement that last coal deliver, avoid the leather belt up the pile up of coal, also protected the leather belt. Lose the coal distance to control the system with the PLC, not only carried out the automation management that equipments circulate and supervision, raise the credibility and safeties of the system, but also improved the work environment, raise the business enterprise economic performance and work efficiencies. therefore the system bears certain practical applying significance and popularizing value .