The　pull-in　phenomenon　is　an　important　sign　of　instable　movement　for　electrostatic　micro-resonators.　In　present　paper,　the　problems　of　homoclinic　orbits　and　homoclinic　bifurcation　motion　in　a　typical　triple-well　potential　system　with　non-Z2　symmetric　and　higher-order　nonlinear　terms　are　studied,　which　is　used　to　describe　corresponding　nonlinear　dynamical　behaviors　of　pull-in　and　complex　vibration　phenomena　in　typical　micro-resonator.　For　the　complexity　between　the　equilibrium　points　and　the　phase　space　curves　in　triple-well　potential　system,　the　non-Z2　symmetric　homoclinic　orbits　that　are　corresponding　to　the　pull-in　phenomenon　are　discussed　under　a　certain　energy　input　condition.　Because　the　fact　of　the　air　damping　in　the　actual　micro-resonator　cannot　be　ignored,　the　autonomous　system　containing　the　damping　terms　is　studied　directly.　The　further　improved　Padé　approximation　method　can　be　applied　to　directly　obtain　analytical　expressions　of　special　homoclinic　orbits　with　completely　non-Z2　symmetry　in　corresponding　conservative　system,　which　contain　not　only　the　conventional　Z2　symmetric　nonlinear　terms,　but　also　the　non-Z2　symmetric　and　higher-order　nonlinear　terms.　In　addition,　the　phase　diagrams　and　bifurcation　parameter　curves　of　homoclinic　orbit　in　corresponding　autonomous　system　are　obtained　when　the　homoclinic　bifurcation　occurs.　The　present　method　is　valid　by　comparing　with　the　phase　diagrams　of　homoclinic　orbits　from　numerical　method.　Copyright　©　(2018)　by　International　Institute　of　Acoustics　&　Vibration.All　rights　reserved.