The invention discloses a water-draining device for a flat plate type pathological toaster. The water-draining device comprises a V-shaped bracket, a wedge-shaped support base and water-absorbing cotton; the water-absorbing cotton is paved on the V-shaped bracket; the V-shaped bracket is fixed on the wedge-shaped support base. The invention also discloses the flat plate type pathological toaster with a water absorbing device. The flat plate type pathological toaster comprises a toasting platform. A front inclined angle on one side of the V-shaped bracket of the water-draining device is adjustable. The water-draining device is closely combined with a front plate of the toasting platform. The flat plate type pathological toaster and the water-draining device thereof disclosed by the invention can quickly remove a water film between a tissue paraffin section and a glass slide, so that the expansion and displacement of the tissue paraffin section can be prevented.