Abstract: According to characteristics of intrinsic safety electrical equipments used in coal mine, a signal isolator for explosion-proof and intrinsic safety computer used in coal mine was designed, design of hardware circuit of the isolator was mainly introduced in this paper. The isolator is used to connect main computer of intrinsic safety computer with external input/output devices, which can real-timely transmit input data with keyboard and has good function of signal isolation and anti-interference performance.