We point out the weak points of oxidation ditch excess activated sludge thickening by cavitation air floatation process. out in this paper and the reasons for such weak points are analyzed, and some advanced measures are put forward and. a mModified cavitation air flotation (MCAF) equipment MCAF10 for oxidation ditch sludge thickening has been developed. The flocculant FO4440SH with 1.0 kg/tDS was added with 1.0 kg/tDS and the 0.2kg/tDS of the surfactant 1227 were adopted with addition of 0.2kg/tDS. When the CAF5 was employed to thicken oxidation ditch excess sludge, the optimal solid loading was 230kgMLSS/m3·d, and the hydraulic loading was 90 m2/m3·d, and the SS in the effluent was 200～250mg/L;. When the MCAF10 was used to thicken oxidation ditch excess activated sludge, the optimal solid loading was 270kgMLSS/m3·d, hydraulic loading was 110 m2/m3·d, and the SS of the effluent was 100～150mg/L. The experimental results indicate that the modified cavitation air flotation (MCAF) equipment is more suitable for sludge thickening.