In　this　paper,　the　silicon　carbide　(SiC)　nanoparticle　colloidal　solution　is　obtained　by　using　the　femtosecond　(fs)　laser　ablation　in　deionized　water.　The　spherical　nanoparticles　are　uniform　in　size　with　an　average　diameter　of　2.84　nm　analyzed　by　transmission　electron　microscope　(TEM).　X-ray　diffraction　patterns　(XRD)　show　that　the　crystal　structure　of　the　nanoparticles　is　still　4H-SiC.　Absorption　spectrum　shows　strong　absorption　of　SiC　colloidal　solution　in　ultraviolet　region.　The　optical　nonlinearity　of　SiC　nanoparticles　colloidal　solution　is　investigated　by　the　Z　scan　experiment,　it　is　found　that　the　SiC　nanoparticles　have　reverse　saturation　absorption　characteristics.　The　nonlinear　absorption　coefficient　beta　is　measured　to　be　about　3　x　10-13　m/W.