The invention discloses a device and a method for dredging a discharge valve of a polyurethane foam gap filler pot. The device at least comprises a drilling bit, a drill body and a drill handle, wherein the drill bit is positioned at the front end of the drill body; the drill handle is arranged at the back end of the drill body; the drill body is provided with feeding grooves; each of the feedinggrooves is of spiral line shape and the feeding grooves are distributed on the whole drill body circularly and continuously; and the radial direction of the drill handle is provided with a plurality of through holes. The drill body is fed into the discharge valve of the polyurethane foam gap filler pot to be dredged; the drill bit is inserted into the bottom end of the discharge valve; and the drill handle is rotated to drive the bottom end of the discharge valve to twist to loose polyurethane foam plastic solidified in the discharge valve so that the solidified polyurethane foam plastic is separated from the discharge valve. The device and the method effectively solve the problem that the polyurethane foam plastic is adhered to and solidifies the discharge valve, and have the advantage of simple and convenient operation.