Flow　is　an　important　parameter　in　the　evaluation　of　injector　performance.　To　investigate　the　effect　of　injection　pressure　on　discharge,　along　with　performing　a　computational　fluid　dynamics　(CFD)　three-dimensional　simulation,　we　built　a　scale-hole　injector　nozzle　to　investigate　the　effect　of　the　inlet　pressure　of　a　diesel　nozzle　on　flow.　We　analyzed　the　variation　law　of　cavitation　flow　inside　the　nozzle　with　changes　in　inlet　pressure　and　the　effect　of　cavitation　flow　on　the　flow　of　fuel　oil　inside　the　nozzle.　The　results　show　that,　as　the　outlet　backpressure　remains　constant　with　increases　in　inlet　pressure,　cavitation　occurs　at　the　nozzle　entrance　and　develops　toward　the　outlet.　When　the　cavitation　area　at　the　inlet　section　reaches　its　maximum　value,　it　holds　constant　and　the　fuel　mass　flow　rate　steadily　increases.　The　development　process　of　the　discharge　coefficient　(Cd)　can　be　divided　into　three　stages:　at　Pind　is　constant　and　related　only　to　the　nozzle　structure;　at　0.8　MPaind　sharply　decreases　and　is　related　only　to　the　shrinkage　coefficient　and　cavitation　number　in　the　inlet　section;　at　Pin＞1.8　MPa,　Cd　is　related　to　the　cavitation　number;　as　the　inlet　pressure　continues　to　increase,　the　cavitation　number　approaches　1　and　Cd　tends　to　become　increasingly　stable.　©　2018,　Editorial　Department　of　Journal　of　HEU.　All　right　reserved.