Using?analytical pure Al(OH)3，SiO2，TiO2 as raw materials, Effect of TiO2 on the sinterbility and microstructure of mullite synthesized from Al(OH)3? and SiO2 was investigated in this paper by XRD、SEM and EPAX. Results show that TiO2 can promote the sintering when the amount of it is below 6%, the sinterbility of samples become better with the increase of the amount of TiO2, microstructure of samples densify gradually, and the best effect was achieved when the amount of TiO2 is 6%. It was shown by XRD analysis that no Al2TiO5 present when the amount of TiO2 is below 6%,TiO2 existed in the form of solid-solution and glass phase; When the amount of TiO2 is excess 6%, the sinterbility of samples become worse with the increase of TiO2? added, microstructure of samples began to loosen, Al2TiO5 can observed in samples and its amount increase with the increase of TiO2.