Abstract: After the formation of water-filled goaf in coal mines, the distribution patterns and locations are different and unclear. Therefore, it can easily cause serious water hazards. In order to accurately locate the water-filled goaf and study its electromagnetic response characteristics, the authors chose the Datong Majiliang coal mine as the engineering background, used acrylic glass shelves as the experimental platform, and took similar simulation materials as each rock layer to design the physical experiment of transient electromagnetic detection in the water-filled goaf under different water accumulation and existence situations of collapsed rock masses. The results demonstrate that, when the goaf is filled with water, the induced electromotive force curve will be affected by the low resistance effect during the attenuation process and produce an abnormal "upward" phenomenon, and the greater the water filling, the more obvious the abnormal amplitude is. The existence of collapsed rock mass will limitedly weaken the abnormal interference of low resistance. When the goaf is not filled with water, the induced electromotive force curve decays normally, and the impact of the collapsed rock mass is negligible.