The invention provides a sedimentation pool for sewage purification. The sedimentation tank comprises a sedimentation tank, sediment carrying equipment, a sediment recovery chamber arranged at an output end of the sediment carrying equipment and a flocculent sediment catching chamber arranged in the sedimentation tank, wherein a sewage inlet is arranged at the bottom end of the sedimentation tank, the sediment recovery chamber is formed on one side opposite to the sewage inlet, the flocculent sediment catching chamber is connected with the flocculent sediment recovery chamber, the bottom surface of the flocculent sediment catching chamber is formed by arranging a plurality of rods at intervals and in parallel, a net is arranged in the middle of the flocculent sediment catching chamber, flocculent sediment catching bodies are arranged between the net and the rods, a flocculent sediment catching body putting chamber is formed on one side of the flocculent sediment catching chamber, a screw conveyor for putting and a screw conveyor for recovery are arranged in the flocculent sediment catching body putting chamber and the flocculent sediment recovery chamber respectively, the screw conveyor for recovery is connected with a circulating cylinder extending into the flocculent sediment catching body putting chamber, and a nozzle spraying clear water into the circulating cylinder is arranged above the circulating cylinder. The sedimentation pool for sewage purification occupies a small area and is low in cost.