Using　titanium　sulfate　containing　wastewater　as　the　raw　material,　and　by　homogeneous　precipitation　method,　nanosized　TiO2　was　prepared　in　this　paper.　The　involved　reaction　processes　are　as　follows.　The　titanium　sulfate　reacts　with　water　to　produce　titanium　oxysulfate.　The　later　changes　to　metatitanic　acid　by　thermal　hydrolysis.　Heat　treat　treating　and　dehydrolyzing　make　metatitanic　acid　to　transform　titanium　dioxide.　There　are　still　some　transformations　after　further　heat　treatments.　The　amorphous　titanium　dioxide　transforms　to　crystalline　anatase.　The　phase　transformation　from　anatase　to　rutile　takes　place　at　higher　temperature.　Mono-phase　anatase　could　be　obtained　after　heat　treating　between　350°C　and　700°C.　The　grain　size　of　anatase　increases　from　9　nm　to　68　nm.　Dual-phase　structure　of　anatase　and　rutile　are　exists　between　700°C　and　800°C.　The　grain　size　of　rutile　increases　from　83　nm　to　109　nm　from　800°C　to　900°C.　Mono-phase　rutile　could　be　obtained　after　heat　treating　higher　than　900°C.