In　order　to　achieve　simply　and　effectively　the　ideal　edge　of　a　medical　image　and　thus　perform　an　effective　medical　diagnose,　a　fast　edge　detection　method　based　on　the　combination　of　fuzzy　subsets　is　developed.　We　partition　an　image　into　two　portions:　the　edge　portion　and　the　non-edge　portion.　Non-edge　portion,　consisting　of　the　objects　and　its　background,　is　removed　from　an　image;　the　remainder　is　image＇s　edge.　Considering　the　fuzziness　of　image＇s　edge,　some　fuzzy　operations　can　be　carried　out.　We　firstly　partition　the　gray-level　histogram　into　several　sub-regions　and　operate　corresponding　fuzzy　subsets.　Finally,　image＇s　edge　is　obtained.　Experiment　results　show　as　compared　with　Sobel　operator　or　Prewitt　operator,　that　the　described　method　is　more　excellent.