Abstract: A serial field bus communication protocol is proposed, which is suitable for the monitoring system of coal mine belt conveyor. At first, the fieldbus protocol standard is introduced, and for the characteristics of conveyor system of coal mine, get conclusion from analysis of the protocol, the protocol should meet simplicity, reliability, real-time,etc.. And then the protocol architecture design is introduced in detail, the mechanism and strategy of improving the reliability of the protocol and finite state machine. This protocol has achieved good results in the application of monitoring system of coal mine belt conveyor, the result shows that the design meets the requirements completely.