Abstract: In view of problem of diversity existed in signal output forms of analog sensor, an intrinsic safety current-frequency conversion circuit based on PIC single-chip microcomputer was designed. The circuit uses intrinsic safety power supply, and converts analog current signal into voltage signal through grounded sampling resistance with high precision and the signal is sent to A/D sampling interface of PIC single-chip microcomputer, then the signal is converted into frequency signal after processed by software. The actual application shows that the circuit can meet with requirements of various current type sensors accessed in coal mine safety monitoring and control system.