By　adding　small　amount　of　TiO2,　aluminum　slag　could　be　used　to　synthesize　cordierite.　α-Al2O3,　TiO2　and　dehydrated　talc　could　generate　solid　solution　to　accelerate　the　solid-state　reaction　to　form　cordierite.　The　experimental　results　show　that　the　content　of　cordierite　increases　with　the　increase　of　TiO2　added.　3.0%　of　TiO2　is　determined　to　be　the　best　amount,　because　all　crystalline　substances　are　converted　into　cordierite　at　this　content.　Philips　X＇pert　plus　software　analysis　shows　that　when　the　content　of　TiO2　is　from　0　to　1.0%,　cordierite　has　the　same　hexagonal　structure　as　the　single　crystal　and　the　lattice　parameters　change　slightly;　when　the　content　of　TiO2　is　from　1.0　to　2.0%,　the　cordierite　still　keeps　hexagonal　structure　but　the　lattice　parameters　change　greatly;　when　the　content　of　TiO2　is　from　2.0　to　3.5%,　the　cordierite　is　converted　from　hexagonal　into　rhombic　and　the　lattice　parameters　change　accordingly.