It　is　significant　to　discuss　the　influence　of　impurities　on　the　synthesis　of　cordierite,　and　it　will　help　us　to　determine　the　permitted　contents　of　different　impurities　in　the　raw　materials,　thus　the　basis　for　selecting　raw　materials　is　established.　XRD　and　SEM　techniques　were　used　to　analyze　the　crystalline　structure　of　each　specimen.　Semi-quantitative　software　was　applied　to　calculate　the　content　of　crystalline　phases.　Philiphs　X＇pert　plus　software　was　utilized　to　characterize　the　cell　parameters　of　each　crystalline　phase.　The　results　suggest　that　the　content　of　CaO　from　1.2wt%　to　2.5wt%　is　beneficial　to　the　synthesis　of　cordierite,　but　that　from　2.5wt%　to　2.8wt%　will　reduce　its　content.　Therefore　2.5wt%　of　CaO　is　the　best　content,　and　at　the　same　time　the　amount　of　cordierite　is　up　to　91%.　Plus　software　analysis　shows　that　when　the　content　of　CaO　is　1.2wt%,　cordierite　has　the　same　structure　as　single　crystal　and　the　unit　cell　parameters　change　slightly;　when　it　changes　from　1.2wt%　to　2.8wt%,　the　cordierite　structure　turns　from　hexagonal　to　tetragonal　and　the　cell　parameters　are　changed　greatly.　Mg-Al　spinel　structure　changes　from　cubic　to　tetragonal,　and　the　unit　cell　parameters　also　have　great　changes.