The invention discloses a sewage sedimentation device convenient for cleaning sinking garbage and increasing aeration rate. The device comprises a sedimentation tank, an aeration tank is fixedly connected to one side of the sedimentation tank through a connecting pipe; a decontamination motor is fixedly connected to the side, away from the connecting pipe, of the sedimentation tank through bolts;a KS02Y controller is fixedly connected to the side, near the decontamination motor, of the sedimentation tank through bolts; and a hydraulic cylinder is installed at the inner bottom end of the sedimentation tank. According to the device, the hydraulic cylinder, a dirt pushing plate, a telescopic rod, a cylinder, an oil pump, an oil pipe, the decontamination motor, a rotating screw rod, a movingrod, a bottom-end cleaning plate, a top-end cleaning plate and a spring are arranged, when sediment in the sedimentation tank reaches a certain limit of the sedimentation tank, the decontamination motor is started by using the KS02Y controller, and the dirt pushing plate pushes dirt above the sedimentation tank, so that the settled dirt at the bottom of the sedimentation tank can be easily moved and cleaned, a sewage discharge pipe is not be blocked, and the sewage does not accidentally flow to a sedimentation processing station, therefore, the processing efficiency is improved.