Al2O3/de-ionized　water　nanofluids　of　different　volume　fractions　with　different　surfactant　mass　fractions　are　prepared　by　two-step　method.　Thermal　conductivities　of　the　suspensions　are　measured　by　a　Hot　Disk　thermal　constant　analyzer.　The　uncertainty　of　liquid　thermal　conductivity　measurement　is　within　1.5%　at　room　temperature　according　to　the　accuracy　verification　test　of　de-ionized　water.　Effects　of　two　kinds　of　surfactants　-　sodium　dodecyl　sulphate　(SDS)　and　polyvinylpyrrolidone　(PVP)　-　on　the　stability　and　thermal　conductivity　of　Al2O3/de-ionized　water　nanofluids　are　analyzed　respectively.　Results　show　that　surfactant　plays　an　important　role　in　dispersing　the　nanoparticles　into　the　base　fluid　and　improving　the　stability　of　Al2O3/de-ionized　water　nanofluids.　Non-ionic　surfactant　PVP　shows　better　positive　effects　than　anionic　surfactant　SDS　on　the　dispersion　and　stability　of　the　nanofluids.　The　highest　thermal　conductivity　occurred　at　an　optimal　concentration　ratio　of　surfactant　mass　fraction　and　particle　volume　fraction,　where　the　ratio　is　partly　associated　with　the　particle　size　and　decreases　with　the　increase　of　particle　volume　fraction.　(C)　2014　Elsevier　Masson　SAS.　All　rights　reserved.