Based　on　the　discontinuous　cutting　edges,　a　generalized　geometric　model　for　indexable　milling　cutters　was　established　and　a　micro-element　method　for　the　indexable　inserts　of　each　layer　each　tooth　was　proposed.　According　to　the　shape　features　of　an　indexable　end　mill　cutter,　the　three-dimensional　model　of　the　cutter　body　was　expanded　to　the　two-dimensional　structure.　The　plane　coordinates　were　used　to　describe　the　geometric　parameters　of　the　various　parts　of　the　cutter　body,　and　then　the　two-dimensional　micro-expression　for　each　edge　of　each　tooth　was　determined.　The　forming　milling　cutter　for　processing　the　three　typical　processing　surface　of　turnout　and　tip-rail　was　taken　as　the　research　object,　a　cylindrical　cutter　body　geometry　model　and　a　non-cylindrical　cutter　body　geometry　model　were　built　respectively,　the　mathematical　geometric　models　were　derived,　and　the　formulas　for　calculating　geometrical　parameters　were　given.　And　then,　the　geometric　parameters　of　the　cutting　edge　micro-element　were　obtained　and　the　simulation　on　micro-element　parameters　was　conducted　with　Matlab　system.　This　method　provided　a　new　means　and　theoretical　basis　for　multi-layer　indexable　milling　cutters＇　cutting　force　prediction,　simulation　and　dynamic　stability　analysis.