Abstract: Affected by karst and goaf, several collapse pits have occurred nearby a coal mine in Hunan, endanger the people's life and property. In order to find out the distribution of karst, the opposing coils transient electromagnetic method was used. By doing 6 lines of opposing coils transient electromagnetic method in the survey area, it finds that the known collapse pits have low resistance characteristics. Its detection results and the known situation are very consistent. So, opposing coils transient electromagnetic method has a better capability of exploration in the town. It can provide detailed information for geological hazard investigation of town.