The invention provides a sewer cover with a turning-over block piece.The sewer cover comprises a cover body provided with a barrier hole.Bases are arranged on the two sides of the cover body.The cover body can move vertically in the bases.A vertical reset spring is arranged between the cover body and the lower edges of the bases.The turning-over block piece is arranged on the lower side of the cover body.One end of the turning-over block piece is connected to a turning-over shaft.The two ends of the turning-over shaft are erected on fixing blocks on the lower edges of the bases.Gears are fixed to the two ends of the turning-over shaft.A cavity is formed in the lower side of the cover body.A nut is fixed to an outlet of the cavity.A lead screw penetrates through the nut.The other end of the lead screw is arranged in installing bases on the lower edges of the bases in a rotating mode.A worm is fixed to the lead screw.Threads on the lead screw are matched with the gears.In the walking process of pedestrians, the barrier hole, under the feet of the pedestrians, of the sewer cover can be closed automatically, and small articles are prevented from falling into a sewer accidentally; moreover, after the pedestrians pass by, the barrier hole can be opened automatically, and normal drainage is not influenced.