On　the　XUD-9　diesel　test　bench,　using　the　recommended　standard　of　China　Petrochemical　Industry　Association　(CPIA)　SH/T-2005　Test　methods　of　the　diesel　nozzle　coking,　the　influence　of　different　fuels　on　the　injection　coking　of　diesel　engine　are　presented.　The　results　show　that:　The　adding　affective　diesel　detergents　decrease　the　nozzle　coking;　There　is　a　large　gap　between　internal　and　external　of　the　diesel＇s　cleaning　performance.　©　2011　IEEE.