Magnesium　aluminate　spinel　(MgAl2O4)　was　prepared　by　using　waste　slag　from　an　aluminum　factory　and　(MgCO3)4·　Mg(OH)2·5H2O　as　the　main　starting　materials.　The　influence　of　titanium　dioxide　(TiC＞2)　mineralizer　on　the　crystalline　structure,　unit　cell　parameters　and　microstructures　were　discussed.　X-ray　diffraction　and　scanning　electron　microscope　were　used　to　characterize　the　crystalline　phases　and　microstructures.　Philips　plus　software　and　Rietveld　quantification　techniques　were　used　to　characterize　and　calculate　the　target　phase.　The　results　show　that　the　amount　of　synthesized　MgAl2O4　and　the　unit　cell　parameters　increased　with　TiO2　content　increasing　when　its　content　was　lower　than　2%　(in　mass,　the　same　below).　The　greatest　amount　of　MgAl2O4　(92%)　was　observed　with　2%　of　TiO2,　which　was　considered　to　be　the　best　content.　Titanium　dioxide　can　react　with　MgAl2O4　to　form　solid　solution　when　its　amount　is　less　than　2%;　otherwise,　it　will　form　a　compound.