The invention discloses a novel mechanical stirring clarification tank. The novel mechanical stirring clarification tank comprises a steel-made cylindrical first reaction chamber, a steel-made second reaction chamber, a stirrer, a mud scraper, a water inlet pipe, a water outlet pipe and the like, wherein the steel-made cylindrical first reaction chamber is located in the middle of the steel-made second reaction chamber; a stirrer impeller for stirring and lifting raw water and circulating sludge is arranged at the bottom or the middle part or the upper part of the steel-made cylindrical first reaction chamber; the lower part of the second reaction chamber is provided with a sludge contact region and is provided with the mud scraper; the outer wall of the steel-made second reaction chamber is in a straight barrel shape or a trumpet shape; a sludge separation region is arranged between the outer side of the second reaction chamber of the clarification tank and the inner wall of the clarification tank; rotary shafts of the mud scraper and the stirrer are coaxial shaft sleeve type structures; and the rotary shafts are driven by transmission devices with different rotary speeds respectively. According to the novel mechanical stirring clarification tank, the technical problems of a traditional mechanical stirring clarification tank that the concentration of reflowing sludge is low, the water treatment effect is not ideal, the equipment maintenance quantity is great, the civil construction difficulty is great and the like can be solved.