Old goaf water is one of the common types of water disasters in coal mines, which has the characteristics of fierce water outburst, large water inflow and strong destructiveness. The old kilns in many areas have a long history of mining. In modern times, due to the non-standard management of individual small coal kilns, the drawings of the location, scope and amount of water in the goaf are missing, and the exploration and prevention are difficult. The conventional ground geophysical prospecting method is limited by the surface topography, and the underground geophysical prospecting method is limited by the general technical requirements of coal mine instruments and equipment. The detection distance is limited, and it is generally difficult to accurately determine the water accumulation range of the goaf water. The emergence of ground-air electromagnetic exploration method points out the direction for the exploration of old goaf water in coal mines. Taking No.6 mining area in the south wing of Sunzhuang Mine as an example, this paper carried out ground-air electromagnetic exploration and achieved good exploration results.