The invention discloses a flashboard valve for a chute/canal. The flashboard valve for the chute/canal comprises the chute/canal and two columns of supporting frames, wherein the chute/canal adopts a U-shaped groove structure; the supporting frames are arranged inside a U-shaped groove side by side; a flashboard is inserted into the clearance between the supporting frames; sealing strips for the sealing with the supporting frames are arranged on the flashboard; the clearance between the two columns of supporting frames is greater than the thickness of the flashboard; round through holes are formed in any column of the supporting frames; a rotating shaft is arranged inside the through holes; a plurality of eccentric wheels for controlling the pressing/releasing between the flashboard and each supporting frame are arranged on the rotating shaft at intervals; a rotating handle is arranged at the upper end of the rotating shaft. The flashboard valve is good in sealing performance, simple in operation, long in service life, convenient to maintain, and relatively low in cost.