The air flotation machine is a water treatment equipment for the separation of solid and liquid by the solution air system producing a large number of micro bubbles in the water, so that the air is attached to the suspended particles in the form of highly dispersed micro bubbles, resulting in a state of density less than water. The air flotation device can be used for some impurities contained in the water body whose specific gravity is close to that of water and which are difficult to sink or float by their own weight. Bubbles are introduced into the water to adhere to the floc particles, thus greatly reducing the overall density of floc particles, and by using the rising speed of bubbles, forcing it to float, so as to achieve rapid solid-liquid separation.