Nanogrooves　with　a　minimum　feature　size　down　to　30　nm　(lambda/26)　can　be　formed　directly　on　silicon　surface　by　irradiation　from　two　orthogonal　polarized　1064　nm/10　ns　fiber　laser　beams.　The　creation　of　such　small　nanogrooves　is　attributed　to　surface　thermal　stress　during　resolidification　and　supercooling　with　the　double　laser　beams＇　irradiation.　By　varying　the　pulse　number　and　laser　fluence,　the　feature　size　of　narrow　grooves　on　silicon　surface　can　be　tuned.　The　experimental　results　and　numerical　calculation　of　surface　thermal　behaviors　indicated　that　the　high　repetition　rate　of　the　nanosecond　laser　leads　to　the　incubation　effect　and　different　silicon　optical　and　thermal　properties　during　laser　irradiation.　Resolution　on　this　scale　should　be　attractive　in　nanolithography,　particularly　considering　that　this　method　is　available　in　far　field　and　in　ambient　air.