Injection　flow　of　high　pressure　common　rail　diesel　injectors　can　be　affected　by　carbon　deposition　or　nozzle　wear,　leading　to　cylinder-to-cylinder　variation　of　injection　quantity　and　then　causing　poor　engine　performance.　In　this　paper,　rail　pressure　variation　during　the　fuel　injection　was　investigated　in　a　high-pressure　common-rail　diesel　fuel　system.　The　rail　pressure　was　collected　at　a　frequency　of　10　kHz　on　a　fuel　pump　test　rig　and　its　variation　characteristics　were　obtained　by　a　wavelet　transform　processing　method.　The　relationship　between　the　fuel　injection　flow　and　the　rail　pressure　variation　was　determined.　The　results　show　that　the　rail　pressure　drop　occurs　during　the　fuel　injection,　and　the　rail　pressure　drop　rate　is　monotonically　positively　correlated　with　the　injection　flow　rate.　In　addition,　the　total　amount　of　rail　pressure　drop　caused　by　the　fuel　injection　is　also　positively　correlated　with　the　total　amount　of　fuel　injection.　Multiple　injection　is　found　to　be　little　effect　on　rail　pressure　drop.　In　order　to　ensure　the　same　rail　pressure　drop　for　multi-cylinder　fuel　injections,　a　control　method　based　on　modifying　the　injection　pulse　width　was　proposed　and　the　consistency　of　injection　flow　rate　was　verified　by　experiments.　©　2022,　Editorial　Office　of　the　Transaction　of　CSICE.　All　right　reserved.