This　paper　aims　to　investigate　the　nonlinear　dynamics　of　a　thin-plate　workpiece　during　milling　process　with　cutting　force　nonlinearities.　By　modeling　the　thin-plate　workpiece　as　a　cantilevered　thin　plate　and　applying　the　Hamilton＇s　principle,　the　equations　of　motion　of　the　thin-plate　workpiece　are　derived　based　on　the　Kirchhoff-plate　theory　and　the　von　Karman　strain-displacement　relations.　Using　the　Galerkin＇s　approach,　the　equations　of　motion　are　reduced　to　a　two-degree-freedom　nonlinear　system.　The　method　of　Asymptotic　Perturbation　is　utilized　to　obtain　the　averaged　equations　in　the　case　of　1:1　internal　resonance　and　foundational　resonance.　Numerical　methods　are　used　to　find　the　periodic　and　chaotic　oscillations　of　the　cantilevered　thin-plate　workpiece.　The　results　show　that　the　cantilevered　thin-plate　workpiece　demonstrate　complex　dynamic　behaviors　under　time-delay　effects,　the　external　and　parametric　excitations.