Automatic drainage device for farmland

The invention discloses an automatic drainage device for a farmland. The automatic drainage device for the farmland relates to the technical field of agricultural irrigation and drainage. A photovoltaic panel is fixed to the top part of a rectangular profile and can provide electric energy for a storage battery, and meanwhile, the storage battery can provide a power supply for a coil; device fixing plates are fixed to the left side and the right side of the drainage device; a floater device is fixed to a corner part of one side of the front part of the drainage device, and decides the on and the off of a whole circuit, i.e. decides whether water is drained or not mainly according to a farmland water level condition; and a bottom fixed cone is arranged in the center of the bottom part of the device so as to prevent the device from displacing or leaking water due to bad contact of two sides. According to the automatic drainage device for the farmland provided by the invention, the farmland water layer drainage