A　new　dynamic　model　of　compliant　mechanisms　is　developed　based　on　the　pseudo-rigid-body　model.　The　kinetic　energy　and　potential　energy　of　various　kinds　of　compliant　segments　are　derived　using　numerical　methods　at　first.　The　dynamic　equation　of　planar　compliant　mechanisms　is　then　developed　based　on　the　Lagrange　equation.　The　natural　frequency　is　obtained　in　the　example　of　a　planar　compliant　parallel-guiding　mechanism.　The　numerical　results　show　the　advantage　of　the　proposed　method　for　the　dynamic　analysis　of　compliant　mechanisms.　[DOI:　10.1115/1.4001091]