Based　on　the　pseudo-rigid-body　model　(PRBM),　a　new　pseudo-rigid-body　model　with　prismatic　pair　is　proposed　considering　the　effects　of　transverse　deformation　and　axial　deformation　of　flexible　elements　in　compliant　mechanisms.　The　prismatic　pair　and　revolute　pair　describe　axial　displacement　and　lateral　displacement　of　flexible　element,　respectively.　The　PR　pseudo-rigid-body　model　of　compliant　mechanisms　is　set　up.　A　three-dimensional　optimization　for　the　optimal　characteristic　radius　factors　and　a　linear　regression　for　the　spring　stiffness　coefficient　are　presented.　The　advantage　of　the　new　model　is　illustrated　numerically　through　the　comparisons　with　the　1R,　2R　models　and　compliant　link.