In the presence of O"3, the oxidative decolorization reaction on molasses fermentation wastewater with SnO"2 as a catalyst was studied. The results showed that SnO"2 accelerated the ozone oxidation reaction and the oxidative decolorization of molasses fermentation wastewater was accelerated. Influences on SnO"2 catalytic ozonation activity by precipitants and the calcination temperature were studied by XRD, IR and TG-DSC. SnO"2 prepared by ammonia as the precipitant had higher catalytic activity and a stronger dehydroxylation. The IR spectra of adsorbed pyridine showed that there were Lewis acid sites on the surface of this SnO"2 catalyst. The main factors influencing molasses fermentation wastewater oxidative decolorization were the wastewater concentration, the O"3 concentration, the pH value and the catalyst dosage. The decolorization of wastewater was improved with the increase of the wastewater dilution ratio, the ozone concentration and the catalyst dosage. High activity ?OH was found to be existing with less amount and low concentration in the process of SnO"2 catalyzed ozonation decolorization.