Abstract: According to requirements that gas pipeline equipments and its associated power supply and communication interface must satisfy the "ia" safety explosion-proof grade in mine gas drainage monitoring system, the gas pipeline equipments can be upgraded by increasing an explosion-proof grade conversion interface based on current mine gas drainage monitoring system with the “ib” explosion-proof grade. Power conversion principle with resistive current limiting and trapezoidal output characteristics, and signal conversion principle with resistive current limiting and linear output characteristics were introduced in detail. Related parameters of key components were analyzed and calculated. The test results show that the conversion interface has the characteristics of high conversion efficiency and low frequency distortion, and its output characteristics meet the "ia" safety level requirements.