Sand core filtering device with automatic drainage function

The utility model discloses a sand core filtering device with an automatic drainage function, which comprises a filtering device main body, a liquid outlet formed below the filtering device main body and used for liquid to flow out, a liquid guide pipe connected to the liquid outlet, an electromagnetic valve for controlling whether the liquid in the liquid guide pipe flows out or not, and a control assembly for controlling the electromagnetic valve to be opened and closed, the control assembly comprises two stop blocks fixed on the inner wall of the filtering device main body, a floating rod capable of linearly moving along a channel reserved between the two stop blocks, and a mounting block positioned on the side surface of the floating rod; a proximity switch capable of controlling the electromagnetic valve to open and close is arranged on one side, facing the floating rod, of the mounting block; when the floating rod and the proximity switch are located on the same horizontal plane, the proximity switch co