According　to　the　shape　of　screw,　the　spiral　surface　equation　of　screw　was　established;　and　through　analyzing　the　relative　motion　between　screw　and　formed　milling　cutter,　find　the　contact　conditions　of　screw　and　cutter,　further　deduce　the　meshing　conditions　of　screw　and　cutter,　and　the　contact　line　equation　was　established　based　on　non-instantaneous　envelope　method.　From　the　axial　cross-section　shapes　which　the　contact　line　rotates　around　the　axis　of　cutter　formed　rotary　surface,　the　profile　equation　of　formed　milling　cutter　was　established.　Analyzing　the　causes　of　processing　error　after　wear　of　formed　milling　cutter,　the　tooth　back　curve　equation　was　established,　finally　got　the　profile　equation　of　formed　milling　cutter　have　constant　back　edge.　By　interference　checking　for　profile　equation　of　formed　milling　cutter,　ensure　correctness　of　milling　cutter　profile.　©　2011　Springer-Verlag.