Aerator is a common aquicultural apparatus to help fish and shrimp living and growing. The existing mechanical aerators are divided into three types: paddlewheel aerator, impeller aerator and injector aerator, among which paddlewheel aerator is more widely used. The existing impeller of paddlewheel aerator is featured by single-body structure, large volume, complicated manufacturing technique and high production cost; and due to fixed blade quantity and axial length, it is inferior in application range and universal use.