In　order　to　solve　the　problem　of　flotation　bubbles,　a　new　algorithm　combining　the　fractional　differential,　improved　level　set　and　Watershed　was　proposed.　The　algorithm　includes　three　steps　of　image　enhancement,　bubble　white　spot　extraction,　and　image　segmentation.　In　image　enhancement,　the　fractional　differential　order　was　automatically　determined　on　image　texture　information　by　using　fractal　analysis,　and　the　improved　adaptive　fractional　differential　algorithm　was　used　to　enhance　bubble　edges.　In　bubble　white　spot　extraction,　the　traditional　level　set　algorithm　was　improved,　and　it　was　applied　for　extracting　white　spots　of　bubbles.　In　image　segmentation,　the　internal　and　external　markers　of　bubbles　were　utilized　to　correct　the　gradient　images,　and　finally　the　marked　watershed　segmentation　algorithm　was　used　to　delineate　bubbles.　For　a　number　of　lead　zink　ore　froth　images　with　different　bubble　sizes,　several　traditional　image　segmentation　algorithms　were　compared　with　the　new　algorithm,　and　the　result　showed　that　the　proposed　algorithm　can　improve　the　image　segmentation　accuracy　and　is　effective　in　reducing　the　over-segmentation　problem　and　in　segmenting　flotation　bubbles.　©　2016,　Editorial　Department　of　Journal　of　Sichuan　University　(Engineering　Science　Edition).　All　right　reserved.