The　differential　settlement　of　subgrade,　which　is　an　important　problem　in　the　operation　of　high-speed　railway.　In　order　to　study　the　effects　of　subgrade　differential　settlement　on　the　service　performance　of　CRTS　II　slab　track　and　the　stability　of　train　operation,　a　vehicle-slab　track-subgrade　system　coupling　dynamic　model　was　established.　The　concrete　damage　of　track　structure　was　considered　based　on　damage　mechanics　theory.　Dynamic　simulations　were　carried　out　using　the　proposed　model.　The　results　show　that　the　subgrade　differential　settlement　will　increase　the　dynamic　response　of　the　vehicle　system.　The　dynamic　response　of　the　vehicle　system　is　positively　correlated　with　the　settlement　amplitude.　The　acceleration　of　vehicle　body　and　the　rate　of　wheel　load　reduction　are　sensitive　to　the　subgrade　settlement　within　the　settlement　wavelength　ranging　from　10　m　to　20　m.　Under　the　subgrade　differential　settlement　and　the　dynamic　action　of　the　vehicles,　concrete　damage　occurs　earlier　in　the　supporting　layer　and　the　concrete　damage　variable　of　the　supporting　layer　is　larger　compared　to　the　precast　slab.