To　date,　cyanide-assisted　gold　leaching　has　been　considered　to　be　the　predominant　method　for　gold　extraction　owing　to　its　simple　process　and　low　cost.　Increasing　concerns　on　the　toxicity　of　cyanide　have　triggered　the　efforts　to　find　the　non-cyanide　methods　to　extract　the　gold　from　gold　ores　for　the　sake　of　environmental　protection.　In　this　work,　the　leaching　behaviors　of　gold　from　ores　by　using　alkaline　sodium　polysulphide　solutions　were　investigated.　Sodium　polysulphides　were　prepared　by　hydrothermal　method　using　sulfur　and　sodium　sulphide　nonahydrate　(Na　2　S·9H　2　O)　as　precursor　under　alkaline　condition.　Our　results　show　that,　as-prepared　polysulphide　showed　dual　actions:　as　oxidant　and　complexant.　Accordingly,　alkaline　sodium　polysulphide　system　was　applied　to　extract　the　trace-level　gold　from　ores.　It　demonstrates　that,　the　gold-leaching　efficiency　is　dependent　on　the　concentrations　of　sodium　sulphide,　the　ratio　of　sulfur/sodium　sulphide,　the　concentrations　of　sodium　hydroxide,　and　reaction　temperature.　The　optimized　gold-extraction　efficiency　(85%)　was　achieved　under　following　conditions:　pressure　of　1　atm;　ratio　of　liquid　to　solid　at　5:1;　the　concentration　of　sodium　sulphide　and　sodium　hydroxide　at　90　g/L　and　0.8　M,　respectively;　the　sulfur/sodium　sulphide　ratio　at　3;　reaction　temperature　at　80　°C;　reaction　time　for　1　h.　To　reveal　how　the　composition　of　sodium　polysulphide　affects　the　gold　leaching,　the　phases　of　polysulphide　were　characterized　by　combing　X-Ray　Powder　Diffraction,　Laser-Raman　Spectrum,　and　Electrochemical　methods.　The　results　indicated　that,　as-prepared　sodium　polysulphide　mainly　comprises　of　the　sulfur,　sodium　trisulfide,　sodium　tetrasulfide　and　sodium　pentasulfide,　wherein　the　tetrasulfide　and　pentasulfide　are　the　main　activate　reagents　for　gold　leaching.　The　finding　in　this　work　indicates　that,　the　sodium　polysulphide　could　have　a　good　capability　for　Au　extraction　from　Au-bearing　antimony　ore.　©　2017　Elsevier　B.V.