Abstract: In order to study the effect of transient electromagnetic （ＴＥＭ） on the detection of ultra-shallow gob, the goaf of a small coal mine in northern Shaanxi is regarded as the research object, and its TEM response is studied from aspects of numerical simulation and field measurement. Ground electricity model is established according to the condition of the research object at first, and theoretical feasibility is demonstrated on the basis of the difference of resistivity. Secondly, the acquisition parameters are set up according to the theoretical results, measured results are analyzed combined with geological conditions, the range of the gob is inferred. Finally, abnormal area is exposed by ground drilling. The results show that the dead depth of TEM is very small. The minimum detection depth is less than 20 m when loop size is 240 m×240 m. The distribution of the ultra-shallow gob can be detected accurately by TEM.