Mg-Al　spinel　is　synthesized　by　using　industrial　waste-residue　and　basic　magnesium　carbonate　in　the　aluminum　factory　as　the　main　raw　materials.　The　influence　of　sintering　temperature　on　crystalline　structure　and　microstructure　of　Mg-Al　spinel　has　been　mainly　discussed.　The　crystalline　structure　of　sample　is　characterized　by　using　XRD,　SEM　and　relevant　analytical　software.　The　experimental　results　show　that　compared　to　the　conventional　synthetic　method,　the　application　of　waste　aluminum　slag　as　the　raw　material　can　greatly,　decrease　the　synthetic　temperature.　The　content　of　Mg-Al　spinel　first　increases　and　then　decreases　with　the　rise　of　sintering　temperature,　and　its　purity　can　reach　as　high　as　96wt%　at　1550　degrees　C,　which　is　therefore　determined　to　be　the　optimum　synthetic　temperature.　SEM　observations　demonstrate　that　as　the　rise　of　sintering　temperature,　the　grain　of　Mg-Al　spinel　grows　up　obviously　with　typical　octahedral　characteristic　appearance.