The　surface　modification　by　ultra-fast　laser　could　regulate　the　mechanical　properties　of　hard　and　brittle　materials.　Since　silicon　carbide　(SiC)　is　too　hard　to　be　machined　with　acceptable　removal　rate　and　quality　by　mechanical　abrasives,　and　femtosecond　laser　(fs-laser)　assisted　grinding　could　be　a　potential　method　to　improve　the　machinability　of　SiC.　Under　fs-laser　modulating,　SiC　surface　could　be　modified　to　generate　laser-induced　periodic　surface　structures　(LIPSS).　Understanding　the　mechanical　properties　and　material　removal　mechanism　of　the　LIPPS　surface　is　crucial　to　accomplish　a　high　efficiency　and　quality　machining　process.　This　paper　aims　to　investigate　the　effects　of　fs-laser　modification　on　the　mechanical　properties,　removal　mechanism,　removal　efficiency,　and　microstructure　changes　of　4H-SiC　surface　during　removal,　together　with　those　of　the　original　4H-SiC　surface　for　comparison.　The　hardness　and　elastic　recovery　ability　of　the　modified　layer　are　determined　by　nanoindentation　test,　and　the　nano-scratch　test　is　adopted　to　study　the　materials　removal　behavior.　The　removal　efficiency　and　the　quality　of　the　modified　surface　is　significantly　improved.　Phase　transformation　is　observed　in　the　scratching　area,　which　reveals　the　existence　of　ductile　mode　removal.　Moreover,　the　stress　distribution　and　the　change　of　scratching　force　on　the　surface　of　SiC　before　and　after　modification　are　studied　by　finite　element　method　(FEM).　The　results　show　that　the　stress　distribution　and　transmission　when　scratched　on　the　modified　surface　is　lower　than　that　of　the　original　surface,　and　the　scratching　force　under　the　same　scratch　conditions　is　greatly　reduced.　With　the　understanding　of　materials　removal　behavior　from　the　whole　process　of　deformation,　phase　transformation,　and　separation　of　LIPPS　from　substrate,　then　the　fs-laser　modification　of　SiC　could　be　evidenced　as　an　effective　method　to　improve　the　grinding　efficiency　and　quality　in　mass　production　of　industry.