The invention discloses a drainage circuit and a control method. The drainage circuit comprises a guide device used for detecting the current water level of a coal mine; a relay separately connected with the guide device, and used for controlling the on-off of a water pump according to the current water level of the coal mine. According to the drainage circuit and control method provided by the invention, the technical problem that in related technologies, water is easy to agglomerate in the coal mine, so that the drainage efficiency is low and a lot of manpower resources are wasted is solved.