A　multi-walled　carbon　nanotube　(MWNT)/silica　xerogel　composite　was　prepared　by　sol-gel　technique　and　characterized　by　Raman　spectroscopy　and　transmission　electron　microscopy.　The　nonlinear　optical　property　of　MWNTs　in　liquid　suspension　and　solid　state　matrix　were　investigated　separately　by　open　aperture　Z-scan　method,　using　532　and　1064　nm　nanosecond　laser　pulses.　The　results　show　that　both　MWNT　composite　and　suspension　are　nonlinear　efficient　at　1064　and　532　nm,　while　MWNT　composite　may　be　more　suitable　for　practical　use　because　of　their　better　nonlinear　effect　and　possibly　nondestructive　nonlinear　absorption　mechanism.　©　2005　Elsevier　B.V.　All　rights　reserved.