Abstract: The paper put forward a design scheme of personnel-evacuating warning system of coal mine underground on basis of existing status of underground communication system of Tianzhuang Coal Mine, introduced working principle, functions and realizing method of each component of the system in details, and took underground gas accident as an example to describe working flow of the system. The system, which is based on technology of digital broadcasting amplification and takes industrial Ethernet as transmitting medium, can broadcast preplan information to each underground working face according to alarming information and realize function of real-time voice communication, which provides reliable technique for mine emergency rescue.