Abstract: In the detection of the mined-out area in a coal mine of western Linfen, the author used the PROTEM67D transient electro-magnetic exploration system, selected suitable work facilities and, through scientific experiment, determined the appropriate work pa-rameters. According to an analysis of the transient electromagnetic electric characteristics of the local known mined-out area, the inter-pretation method was established for the apparent resistivity variation range suitable for the division of the mined-out area, the analysis and interpretation of the electric character sectional drawing for the whole exploration area were conducted and, on such a basis, the limits of the mined-out area and the mined-out waterlogged area were delineated. It is proved that the geological effects are satisfactory.