Abstract: In order to better improve the air flotation efficiency, the influence of orifice diameter of releaser on bubble generation was investigated based on the working principle of TS type dissolved gas releaser on the ground of pressure dissolved gas floatation method, using CFD fluid simulation analysis and combined with pressure dissolved gas method microbubble generation experiment platform. According to the simulation analysis and test results, under the same dissolved gas pressure, the velocity gradient and the maximum turbulence kinetic energy inside the release device decrease with increased orifice diameter. After the release, the bubble diameter formed in the process of air floating presents a change law of first decreasing and then increasing. Therefore, it is necessary to select appropriate diameter of the release nozzle.