Abstract: Parasitic circuits may cause serious electromagnetic interference faults in power systems, especially in complex circuits, and their concealment increases the difficulty of detection and brings great challenges to system security. To solve this problem, a non-contact AC parasitic loop detection device based on the principle of electromagnetic induction is investigated in this paper. By designing a highly sensitive electromagnetic induction probe and a low-noise amplification circuit, the device realizes the detection of weak AC currents and demonstrates anti-interference performance in complex electromagnetic environments. Experiments show that the device is able to detect AC parasitic loops with extremely high reliability.