Abstract: In view of the problem that the loading side of existing mine-used equipment switch is the non-shielded cable and the feed state sensor is not easy to install, and tests are susceptible to be disturbed and misjudged, we design a new type of feed state detection sensor, we analyze the general detection principle of the mine-used feed sensor in detail, and the reasons of easy to be disturbed and misjudged. We introduce the overall design of non-shielded type mine-used feed state sensor and elaborate signal acquisition device for weak electric field leaked around non-shielded cable in detail. The application results show that the sensor has the advantages of easy installation, not easy to be disturbed by leaked electric field around shielded cable, accurately accessing feed state to monitoring system to realize real-time monitoring of the switch state from ground.