The Anjialing No. 1 Coal Mine in Shanxi Province, China, contains a complicated old goaf and an unknown water distribution that hold high potential for serious water hazards. Due to poor detection resolution, previous attempts have failed to determine the scope of the old goaf and the water distribution in the mine by separate use of various exploration methods such as seismic method, direct current resistivity, audio magnetotellurics, controlled-source audio-frequency magnetotellurics, and transient electromagnetics. To solve this difficult problem, a combination of the wide-field electromagnetic method and the flow field fitting method with three-dimensional resistivity data inversion was applied to determine the precise scope of the goaf and the locations where water is present, and to identify the hydraulic connection between the water layers so as to provide reliable technical support for safe coal production. Reasonable results were achieved, with all these goals being met. As a result, a mining area of nearly 4 km² has been released for operation.