This　paper　proposes　an　approach　for　calculating　the　transmission　ratio　of　nutation　drive　based　on　the　working　principle　of　the　nutation　movements.　Then,　the　analysis　of　the　influences　for　the　nutation　angle　on　the　transmission　ratio　is　carried　out.　The　controllable　tooth　profile　modelling　for　external　and　internal　spiral　bevel　gears　with　double　circular-arc　is　proposed.　Based　on　the　proposed　tooth　profile　modeling,　the　three　dimensional　modeling　and　virtual　assembly　of　the　nutation　drive　have　been　further　completed.　Finally,　the　kinematical　simulation　is　preceded　in　the　simulating　system　and　the　comparative　results　have　been　accomplished　between　the　simulation　results　and　the　theoretical　ones　of　the　transmission　ratio.