The plastic hollow float has the characteristics of stable center of gravity, overlapping sides with sides, and good covering effect. It can be widely used in various water baths, horizontal acid storage tanks, condensate storage tanks and demineralized water tanks in water treatment, and greatly reduces heat. Dissipate, reduce water pollution by acid mist and carbon dioxide and oxygen in the air, protect the health of operators, and achieve the effects of maintaining water quality, saving energy and purifying the environment.