Abstract: In order to detect the roof water hazard in underground working face, taking the roof of working face 160201 of Yangchangwan coal mine as an example, the transient electromagnetic method was adopted to detect at different direction the water-conducting crack zone in the roof of air roadway and belt transporter roadway. On this basis, the three-dimensional resistivity data of the transient electromagnetic apparent resistivity of the working face roof were established to analyze the water abundance of water-conducting fractures of different horizons. The results of borehole drainage test show that transient electromagnetic method can accurately and effectively detect the water-conducting cracks in the roof of underground working face.