The actual requirements of voice communication of belt conveyor were analyzed. An implementation scheme of voice communication system for belt conveyor was designed, with analysis of system composition, circuit design and software, the system including upper computer, voice module and alarm, upper computer communicated with the alarm module through Modbus-RTU, transmitting the voice data of the fault alarm and the safety prompt, and the voice module and the alarm module were connected by the analog voice signal. The voice module had the functions of dot, speech and expansion, including battery charging management, pickup signal amplification processing, audio signal speaker playback and dot signal generation. The alarm module used the FreeModbus protocol stack to implement Modbus-RTU communication, and converted the voice playback command transmitted from the host computer into an analog voice signal for transmission along the line. This kind of scheme was applied in the coal mine field, and the system was running stably and achieved the design goal.