The invention relates to a submerged type aerator which is suitable for deep-water area aeration oxygen-enhancing to improve dissolved oxygen saturation in the sewage in the sewage purification biological treatment method, the submerged type aerator adopts a submerged hollow shaft motor to make the air flowing through the ventilation pipe pass through the hollow driving shaft of the motor and enter the underground, and then fed into the water by high-speed rotary jet impeller, and then is stirred by propeller so as to realize water-air mixing, thereby improving saturation of the dissolved oxygen. The invention is widely applied in the fields of petrol, chemical industry, print dyeing, leather, paper industry and medical industry, and sewage treatment of urban population life, and aquaculture, lake and river management, and is suitable for oxygen-filling in various aeration pond, oxidization pond, lake and river.