Abstract: In order to study electromagnetic response features of a water accumulated goaf in a coal mine, a theoretical model of the water accumulated goaf in the mine was established.A transient electromagnetic response curve was calculated and the electromagnetic response features of the typical water accumulated goaf were analyzed.The theoretical calculation results showed that on the premise of the goaf detected had the geophysical conditions, the transient electromagnetic method woul d have an obvious reaction to the water accumulated goaf and a lateral resolution would be high.The transient electromagnetic method would not have an obvious react ion to a high resistance goaf.When the goaf had several layers of water accumulation in vertical direction, a delay effect of the transient electromagnetic would make a | ongitudinal resolution reduced of the transient electromagnetic method and would be hard to distinguish a certain layer level to cause the electromagnetic abnormal in a certain depth scope.The detection application of the water accumulated goaf in Sangshuping Mine showed that the theoretical results and the site actual condition woul d be fitted and the method was real effective.