The invention discloses a device for efficiently removing impurities from sewage. The device comprises a pollution discharge tank, a water inlet tank and a treatment chamber from bottom to top sequentially, wherein a water inlet is formed in the bottom of the side wall of the water inlet tank, a water outlet is formed in the top of the side wall of the treatment chamber, a plurality of filter screens are arranged in the treatment chamber from top to bottom, the sewage enters the water inlet tank from the water inlet and upwards enters the treatment chamber, the filter screens from bottom to top form a parallel-connection structure, the efficiency of removing the impurities from the sewage is increased, and the filter screens are not prone to blockage; a discharge port is formed in one sideof the bottom surface of the water inlet tank, a baffle plate is arranged at the discharge port, a control tank is arranged above the baffle plate, a buoyancy control mechanism is arranged in the control tank, when the filter screens are blocked, the sewage of the water inlet tank enters the control tank, the baffle plate is pulled up by the buoyancy control mechanism, the discharge port is open,water in the water inlet tank and the treatment chamber washes the filter screens from top to bottom and is discharged through a drain outlet. Automatic back wash can be realized without high pressure, so that electric energy is saved, and large-particle impurity pollutants in the sewage can be effectively removed.