γ-Al2O3　nanofluids　of　different　volume　fractions　with　different　mass　fractions　of　sodium　dodecyl　sulphate　(SDS)　and　polyvinylpyrrolidone　(PVP)　are　prepared　by　two-step　method.　Effects　of　temperature　and　two　kinds　of　surfactants　(SDS　and　PVP)　on　the　stability　and　thermal　conductivity　of　γ-Al2O3　nanofluids　are　analyzed.　The　results　show　that　nanofluids　with　non-ionic　surfactant　PVP　are　better　dispersed　than　the　ones　with　anionic　surfactant　SDS.　The　thermal　conductivity　of　nanofluids　increases　at　the　beginning　and　then　decreases　with　the　increase　of　surfactant　concentration.　An　appropriate　ratio　of　particle　and　surfactant　concentration　would　make　a　good　contribution　to　inicreasing　the　thermal　conductivity　of　nanofluids.