The　dynamic　modeling　of　compliant　mechanism　becomes　more　difficult　and　complex　because　of　the　geometric　nonlinear　factor　resulted　by　the　large　deformation　of　flexible　beam.　In　order　to　solve　this　problem,　based　on　the　simplification　principle,　a　new　method　for　its　dynamic　modeling　is　studied　with　the　consideration　of　large　deformation　character　of　flexible　beam.　Three　kinds　of　flexible　beams,　i.e.　end-moment,　end-vertical　force　and　parallel-guided　mode　are　considered　as　research　objects.　With　the　consideration　of　large　deformation　characteristic　and　in　the　combination　of　boundary　condition　obtained　from　the　pseudo　rigid-body　model,　deformation　curve　of　flexible　beam　under　large　deformation　is　obtained　on　the　basis　of　the　least　square　principle.　And　the　kinetic　energy　of　flexible　beam　is　deduced.　Based　on　the　principle　of　energy　conservation,　the　potential　energy　of　flexible　beam　is　easily　calculated　in　the　pseudo　rigid　body　model.　Then　the　dynamic　model　of　parallel　guided　compliant　mechanism　is　developed.　Finally,　the　numerical　analysis　verifies　the　validity　of　the　dynamic　model　by　comparing　with　other　methods.