Abstract：For catalytic ozonation of dimethyl phthalate with alumina as catalyst, the physicochemical properties (pore size, crystal structure and size, surface area, surface groups) and catalytic performance of the catalyst were investigated based on results of nitrogen adsorption-desorption, XRD, TEM, FTIR and activity evaluation. The effects of calcination temperature and particle diameter of the catalyst on its activity were studied. Results show that Al2O3 can significantly increase the effect of such ozonation, and total organic carbon (TOC) removal rate in 120 min can reach 55.1% while only 23.9% with ozone alone. Catalytic performance was affected significantly by calcination temperature and reached maximum at 600 ℃. With the rise of the calcination temperature, the structure of Al2O3 was changed from γ-Al2O3 to θ-Al2O3 then to α-Al2O3, the surface area and pore volume were decreased, crystal size and the surface hydroxyl groups were increased and the catalytic activity was decreased.