Abstract: A series of Ti-modified alumina samples having various TiO2 contents was prepared. The dispersion state of TiO2 on the alumina support was characterized by TEM, XRD and XRF. Furthermore, the effect of TiO2 on the surface hydroxyl groups of alumina support was studied by FT-IR. Results show that Ti species is dispersed on the alumina surface uniformly. The IR absorption peak of alumina at wave number of 3 725 cm-1 is related to weak acidic hydroxyl group bridged with octahedral Al3 + and tetrahedral Al3+, with the loading of TiO2, the H+ of this bridged hydroxyl is substituted by Ti species firstly, followed by substituting H+ of other hydroxyl groups gradually. It can be seen that in wave number range of 1 000—2 000 cm-1 the related medium strong and weak Lewis acid sites of alumina are affected by Ti-modification in certain aspect.