The　piezocone　penetration　test　(CPTU)　is　widely　applied　in　soil　layer　division　and　soil　classification.　However,　its　various　soil　classification　methods　have　certain　applicability　and　limitations.　Five　common　classification　charts　are　analyzed　based　on　two　groups　of　practical　engineering　cases.　The　results　show　that　the　existing　classification　chart　can　well　distinguish　cohesive　soil　and　non-cohesive　soil,　but　there　are　certain　errors　in　the　discrimination　between　silty　clay,　silty　and　silty　sand.　Besides,　most　classification　charts　adopt　the　transitional　zone　method,　which　will　underestimate　the　classification　accuracy.　In　this　study,　according　to　the　actual　test　data　classification　results,　the　soil　behavior　type　index　Ic　is　modified　through　the　soil　behavior　type　index　classification　chart　by　Robertson.　As　a　result,　a　new　method　of　CPTU　based　modified　soil　behavior　type　index　is　proposed　by　modifying　the　concentric　circle　model　to　a　parallel　line　model.　The　application　results　show　that　the　proposed　classification　method　can　well　satisfy　the　classification　of　practical　engineering　soil　and　the　discrimination　between　silty　clay,　silty　soil　and　silty　sand,　respectively.　©　2022,　Editorial　Office　of　Rock　and　Soil　Mechanics.　All　right　reserved.