Abstract: In the early stage of an underground iron mine，the non-pillar sublevel caving method is used to form a goaf，and the full tailings cemented filling technology is used for subsequent treatment. In order to find out the actual distribution of goaf and the effect of filling treatment，ensure the safety of mine production and meet the requirements of hidden disaster-causing census in mines，two geophysical pros⁃ pecting techniques of controlled source audio magnetotelluric method (CSAMT) and natural source surface wave method (micro-motion) are used to carry out special detection work in goaf. A total of 10 detection lines are set up. The results show that there are still 9 goaf affected areas in the mine，of which 3 areas are not fully filled，and the total volume of the unfilled goaf is about 424 700 m3 . The results of geophysical ex⁃ ploration accurately reveal the spatial distribution characteristics of goaf and filling defects，provide reli⁃ able technical guidance for the next targeted treatment of goaf，and have important practical significance for improving the level of mine safety management and control.

Key words: goaf, hidden disaster-causing census, geophysical prospecting exploration, controlled source audio-frequency magnetotelluric, natural source surface wave method