Five　Al2O3　nanofilms　with　thickness　of　20-60　nm　were　deposited　by　atomic　layer　deposition(ALD).　The　surface　roughness　and　microstructure　of　the　deposited　Al2O3　nanofilms　were　characterized　by　three　dimensional　optical　microscopy　and　transmission　electron　microscopy.　The　force-displacement　curves　captured　by　a　hybrid　scanning　electron　microscope/scanning　probe　microscope(SEM/SPM)system　were　analyzed　based　on　Hertz＇s　theory　of　contact　mechanics　for　the　elastic　modulus　of　Al2O3　nanofilms.　The　Hay　model　was　used　to　eliminate　the　influence　of　the　substrate　on　the　measurement　results,　and　the　errors　in　the　model　due　to　the　different　shapes　of　the　indenter　were　corrected.　The　results　show　that,　ALD　Al2O3　nanofilms　is　amorphous,　and　the　surface　roughness　does　not　increase　with　the　increase　of　thickness.　The　elastic　modulus　do　not　show　obvious　small　size　effect,　and　the　measured　value　is　(175±10)　GPa.　Under　the　same　indentation　ratio,　the　smaller　the　film　thickness　is,　the　more　obvious　the　substrate　effect　is.　©　2019,　Materials　Review　Magazine.　All　right　reserved.