Abstract: In order to enhance the flotation effect of pressurized dissolved air flotation,the distribution of bubble size in this process was studied.The size of air bubbles was measured by the laboratory-made image-based air flotation bubble size measuring device.The fitting effects of Nukiyana-Tanasawa distribution,logarithmic normal distribution and normal distribution to the distribution of bubble size on different pressure and octanol alcohol concentrations were compared.The effects of dissolved gas pressure and foaming agent concentration on the size distribution of air-flotation bubbles were investigated.The results show that the bubble size distribution in the pressurized dissolved air flotation accords with the normal distribution law.The pressure of dissolution has a great influence on the bubble size,and with the increase of the pressure of dissolved gas,the Sauter diameter of the air bubble decreases gradually,the bubble size distribution density peak gradually shifts to the small size direction.With the increase of the concentration of octanol alcohol,the distribution of the bubble size is more concentrated,the distribution range is reduced,and the Sauter diameter is gradually reduced.