To　meet　the　needs　of　diesel　engine　industry,　an　IEUP　fuel　injection　system　was　developed.　In　the　IEUP,　multiple　EUPs　were　integrated　into　one　inline-pump　body　to　replace　the　traditional　inline-pump.　Based　on　experiments,　the　IEUP　inject　performance　with　different　pipe　length　and　engine　speed　was　discussed.　The　IEUP　was　applied　to　an　YN4D44　diesel　engine　and　the　inject　flow　was　optimized　in　this　paper.　Experiments　prove　that　the　optimized　IEUP　diesel　is　highly　improved.