In　order　to　understand　the　essential　mechanism　of　mechanical　activation　for　spontaneous　combustion　of　sulfide　ores,　a　typical　sample　was　obtained　from　the　sulfur-rich　mine　to　make　the　mechanical　activation　experiment.　The　surface　morphology　and　microstructure　of　samples　activated　at　different　mechanical　powers　(100,　200,　300,　350,　400,　450　r/min)　were　characterized　by　scanning　electron　microscopy　(SEM)　and　X-ray　diffraction　(XRD)　analysis.　Further　oxidation　experiment　was　made　at　constant　temperature　and　humidity,　and　the　oxidation　mass　gain　rates　of　the　activated　samples　were　compared.　The　results　show　that　small　particles　and　agglomeration　effects　are　formed　after　sulfide　ores　undergo　mechanical　activation　by　different　mechanical　powers.　The　lattice　distortion　of　sulfide　ores　increases　and　the　domain　size　reduces,　and　the　oxidation　rate　accelerates.　Sulfide　ores　are　prone　to　oxidation　after　mechanical　actions　by　the　increased　activation,　which　leads　to　spontaneous　combustion　under　appropriate　conditions　ultimately.　©　2017,　Central　South　University　Press.　All　right　reserved.