Abstract: The key to safe mining of overlying coal seam in goaf is the stability of interlayer rock and the macroscopic integrity of overlying coal seam floor. In order to ascertain the actual situation of the overlying coal seam floor, starting from the study of coal seam occurrence condition and actual survey data, we use mine transient electromagnetic wave detection technology to detect the floor damage range of 1-101 fully mechanized coal mining face in 1^# coal seam, and the goaf, fissure zone and abundance water area and other distribution range under the coal seam floor are determined. The results show that there are two relatively high resistivity anomalies in the range of 300 m, and it is inferred that the fault zone caused by fault structure is poor in water abundance area and there is no goaf distribution in the detection area; there are also 4 relatively low resistivity abnormal areas due to the small coal mines destroy or passing through areas.