Abstract: The traditional intercom along the belt conveyor adopts the analog carrier which is easy to be interfered, and the transmission mode is single and the broken line cannot be detected. In order to solve these problems, this paper designs a digital intercom system, and introduces the structure of the intercom system along the belt in detail, the key technologies of the intercom equipment, such as voice acquisition, voice transmission, voice amplification and voice mixing echo cancellation. It is of great significance to improve the efficiency and safety of belt transportation in coal mine by using belt digital link and collecting and transmitting the key data along the belt.