Abstract: The measurement of the electrochemical polarization effect of rock (ore) in an AC electric field (i.e., the phase between receiving potential different and transmitting current) using spectral induced polarization (SIP) can provide important information for distinguishing ore from non-ore. Based on the deep research on the key technologies of SIP instruments, this study designs a new synchronous correlation detection technology of weak signals, and accordingly improves the prototype for practical purposes, simplifies the circuit structure, and improves the stability of phase measurement of the SIP instruments. The tests in mining areas show that the improved SIP instrument has lower cost, stronger anti-interference ability, higher practicability, and is suitable for large-scale promotion and application.