Because　of　the　complex　structure　of　the　rock　images,　using　the　general　image　processing　methods　to　segment　the　ore-bearing　rock　particle　images　may　cause　uneven,　owe　segmentation　and　over　segmentation　phenomenon.　In　order　to　improve　the　accuracy　of　rock　image　segmentation,　a　kind　of　ore　image　segmentation　algorithm　was　proposed　based　on　graph　theory.　In　this　algorithm,　the　first　step　was　to　reduce　images　by　multi-scale　analysis,　then,　the　ore　image　was　segmented　by　using　Normalized　Cut.　Various　categories　of　ore-bearing　rocks　were　segmented　by　NCut　and　the　segmentation　images　were　compared　with　the　segmentation　results　of　traditional　image　processing　methods　such　as　threshold,　watershed　and　clustering　analysis,　FCM　and　other　processing　methods　in　the　experiment.　The　result　of　the　experiment　showed　that　for　some　specific　rocks,　the　new　algorithm　is　better　than　the　traditional　ones.　©,　2015,　Editorial　Department　of　Journal　of　Sichuan　University.　All　right　reserved.