By　analyzing　the　microstructure　and　mechanical　properties　of　Cu　foil　after　femtosecond　laser　shock　in　different　absorption　layers,　the　absorption　layer　with　better　strengthening　effect　was　selected.　Femtosecond　lasers　were　used　to　impact　strengthen　the　copper　foil　(Cu-nm)　coated　with　a　100　nm　thickness　absorption　layer　and　the　copper　foil　(Cu-µm)　coated　with　a　100　µm　thickness　absorption　layer.　The　microstructure　and　mechanical　properties　of　the　two　samples　were　observed　and　analyzed　by　scanning　electron　microscopy,　electron　backscatter　diffraction,　X-ray　diffraction,　and　microhardness　tester.　After　femtosecond　laser　shock,　Cu-nm　mainly　produced　deformation　twinning,　with　60.9%　increase　in　the　twinning　ratio,　12.8%　increase　in　the　ratio　of　large-angle　grain　boundaries,　and　10.8%　increase　in　microhardness;　Cu-µm　mainly　underwent　dislocation　changes,　with　16%　increase　in　dislocation　density,　9.8%　increase　in　the　ratio　of　small-angle　grain　boundaries,　and　2.2%　increase　in　microhardness.　In　addition,　Cu-nm　produces　greater　residual　compressive　stress　after　femtosecond　laser　shock,　which　not　only　neutralizes　the　residual　tensile　stress　of　the　base　material,　but　also　shows　as　residual　compressive　stress,　while　the　residual　compressive　stress　produced　by　Cu-µm　after　femtosecond　laser　shock　cannot　completely　neutralize　the　residual　tensile　stress　of　the　base　material,　and　still　shows　as　residual　tensile　stress.　A　comparative　study　showed　that　the　femtosecond　laser　shock　on　Cu-nm　achieved　microstructural　twinning,　changed　the　residual　stress　state　and　improved　the　hardness　of　the　copper　foil　surface.　©　2021,　Chongqing　Wujiu　Periodicals　Press.　All　rights　reserved.