Abstract: It is very important for the safe and stable operation of power grid to detect the location and scope of mined-out area under transmission line accurately and efficiently by comprehensive geophysical method. According to the geophysical properties of goaf, resistivity method, electromagnetic method and seismic method are often used to detect goaf, but due to the actual interference and geophysical multi-solution, a single geophysical exploration method is often difficult to achieve ideal results. In this paper, the symmetrical quadrupole section resistivity method and shallow seismic reflection method are used to detect the mined-out area under the high-voltage overhead line. The study shows that the resistivity method and seismic method are mutually validated and complementary, which effectively reduces the multi-resolution of single geophysical method interpretation, and improves the detection resolution and the reliability of interpretation results. It provides an effective basis for delineating goaf.