A series of pseudo-boehmite samples with their sulfate radicals(SO42-) concentration ranging from 0.9%to 3.0%were prepared by the reaction of NaAlO2 solution on Al2(SO4)3 solution. The existing form of sulfate radicals was investi-gated. Results have shown that sulfates in pseudo-boehmite included two parts, the soluble sulfate radicals and the insoluble sulfate radicals, which accounted for 99%of the total amount of sulfate radicals. XRD, low-temperature N2-adsorption, and TEM were used to characterize the properties of these pseudo-boehmite samples. Results have shown that the relative crys-tallinity and crystal size of pseudo-boehmite decreased with the increase of sulfate radicals in the support. In the meanwhile, the bound water content in pseudo-boehmite increased. The TEM images of pseudo-boehmite indicated that the pseudo-boehmite was prone to become amorphous hydrated alumina. However, the effect of sulfate content on the speciifc surface area and pore structure of aluminium oxide was insigniifcant.