The　rules　of　the　influence　of　Cr　ions　with　different　valence　on　the　formation　and　the　crystal　structure　of　ettringite　were　investigated　by　means　of　X-ray　diffraction　and　X-ray　photoelectron　spectroscopy　analysis　test.　The　results　show　that　the　Cr3+ions　slightly　influence　the　formation　inhibition　of　ettringite,　and　its　crystallization　is　extremely　small　on　the　early　hydration　phase,　while　it　is　formed　greatly　on　the　later　hydration　phase,　and　the　crystallization　become　thick　and　big,　and　the　ratio　of　length　to　diameter　of　the　crystal　becomes　smaller　along　with　the　development　of　hydration.　While　Cr6+　ions　show　a　positive　effect　on　the　formation　of　ettringite　at　the　early　hydration　stages,　and　the　crystallization　is　well.　There　is　no　significant　change　on　the　crystalline　form　along　with　the　development　of　hydration.　When　the　SO42-　content　is　plentiful　on　the　hydration　liquid　phase,　both　Cr3+　ions　and　Cr6+　ions　can　form　chromite　ettringite　through　lattice　ion　substitution,　and　Cr3+ions　have　a　larger　influence　on　the　crystal　structure　of　ettringite　than　Cr6+,　and　Al　and　S　atomic　binding　energy　of　ettringite　shows　a　significant　decrease.　The　combination　energy　and　quantity　of　Cr3+　ions　on　ettringite　are　higher　than　that　of　Cr6+　ions.　©　2018,　Editorial　Department　of　Journal　of　Building　Materials.　All　right　reserved.