The invention relates to a sedimentation basin and belongs to the technical field of environmental engineering. The two sides at the bottom of the sedimentation basin are sunk and recessed to the middle, and the whole bottom of the sedimentation basin is inclined towards one side; the sedimentation basin is made of concrete, and ceramics are attached to the inner face of the sedimentation basin; an anti-wave grid is arranged in the middle of the sedimentation basin; a water inlet is formed in one side of the sedimentation basin, and a water outlet is formed in the other side of the sedimentation basin; a sludge discharge channel is formed in the bottom of the sedimentation basin. According to the sedimentation basin, based on the inner surface made of the ceramics, one layer of polytetrafluoroethylene coating is added, so that sediments are effectively prevented from being attached to the inner surface of the basin and easier to collect, and meanwhile, the sedimentation basin is easier to clean. The anti-wave grid is arranged in the middle of the basin, and the inlet and the outlet are arranged at the two ends respectively, so that when water enters, just the water on the water inlet side is agitated, the water on the water outlet side keeps calm, and accordingly the sedimentation time is shortened. The bottom long channel is used for sludge sedimentation and sludge is convenient to clean.