Abstract: Formation resistivity contains abundant formation information, and the accurate description of rock resistivity is particularly important for the resistivity detection interpretation. Based on the systematic analysis of the resistivity characteristics of geotechnical materials, the resistivity formula of unsaturated rock is deduced by combining the Maxwell conductivity theory formula, which is verified to be consistent with Archie's formula. High density electrical method and transient electromagnetic method are used to carry out comprehensive geophysical exploration in the field area, and the goaf and overburden resistivity is interpreted based on the theory of rock resistivity and verified by drilling. The results show that the resistivity of compressed rock positively correlated with the volume strain; there is an electrical abnormal transition zone in the adjacent area of goaf; The height of transition zone is consistent with that of caving and fractured zone. And the resistivity comprehensive exploration can basically reveal the distribution pattern of goaf .