The　influence　of　sintering　time　and　sintering　temperature　on　the　crystalline　structure　of　cordierite　synthesized　from　waste　aluminum　sludge　was　studied　in　this　paper.　The　sludge　was　obtained　from　treating　the　surface　of　Al　finishing　plant.　After　dewatering　its　main　component　is　gamma-AlOOH　which　is　the　coexistence　of　both　crystal　and　amorphous　states.　gamma-AlOOH　has　high　activity　which　can　decrease　the　sintering　temperature　and　help　form　cordierite.　The　results　show　that　the　amount　of　cordierite　increases　with　the　increase　of　sintering　temperature,　and　consequently　the　crystalline　and　unit　cell　parameters　are　changed.　The　best　sintering　temperature　and　sintering　time　are　determined　to　be　1350　degreesC　and　5　h,　respectively..　Under　such　conditions,　the　amount　of　cordierite　phase　is　the　largest.