The　pseudo-rigid-body　body　model　of　a　planar　crank-rocker　four-bar　compliant　mechanism　with　flexural　hinges　is　developed　at　first.　A　new　method　for　calculating　the　driving　torque　is　then　obtained　on　the　basis　of　the　dynamic　analysis　of　the　compliant　mechanism　with　flexural　hinges,　and　it　shows　that　the　flexural　hinges　have　impacts　on　the　driving　characteristics　of　the　compliant　mechanisms.　The　results　of　example　indicate　that　the　peak　driving　torque　is　minimized　by　modifying　the　stiffness　and　the　unstrained　positions　of　the　flexural　hinges.　The　torque　reduction　factor　is　calculated　for　optimally　designed　mechanism.