The　tiny　differences　of　physical　performance　and　chemical　performance　among　monocrystal　silicons　with　various　crystal　surfaces　have　great　effect　on　micronano　processing　results,　and　the　behavior　characteristics　of　different　monocrystal　silicon　surfaces　under　femtosecond　laser　irradiation　are　studied　by　the　electron　backscatter　diffraction　(EBSD)　technology.　The　results　indicate　that　the　amorphous　region　and　the　etching　region　are　formed　on　the　(111)　surface　of　monocrystal　silicon　when　the　energy　densities　of　femtosecond　lasers　are　under　and　above　the　damage　threshold.　However,　the　etching　region　is　formed　only　on　the　(111)　surface　of　monocrystal　silicon　irradiated　by　femtosecond　lasers　with　different　energies.　The　femtosecond　laser　is　widely　used　in　micronano　processing.　The　study　of　the　behavior　characteristics　of　different　crystal　surfaces　irradiated　by　femtosecond　laser　is　beneficial　to　fabricating　novel　micronano　devices.　©　2017,　Chinese　Lasers　Press.　All　right　reserved.