A　method　for　predicting　the　stability　of　thin-walled　workpiece　milling　process　is　described.　The　proposed　approach　takes　into　account　the　dynamic　characteristics　of　workpiece　changing　with　tool　positions.　A　dedicated　thin-walled　workpiece　representative　of　a　typical　industrial　application　is　designed　and　modeled　by　finite　element　method　(FEM).　The　workpiece　frequency　response　function　(FRF)　depending　on　tool　positions　is　obtained.　A　specific　3D　stability　chart　(SC)　for　different　spindle　speeds　and　different　tool　positions　is　then　elaborated　by　scanning　the　dynamic　properties　of　workpiece　along　the　machined　direction　throughout　the　machining　process.　The　dynamic　optimization　of　cutting　parameters　for　increasing　the　chatter　free　material　removal　rate　and　surface　finish　is　presented　through　considering　the　chatter　vibration　and　forced　vibration.　The　investigations　are　compared　and　verified　by　high　speed　milling　experiments　with　flexible　workpiece.