A　synthesis　dinensional　design　method　of　planar　3-RRR　parallel　manipulator　was　studied　to　design　a　flexible　planar　3-RRR　parallel　manipulator　with　high　velocity　and　acceleration.　The　inverse　kinematics　equation,　the　transfer　velocity　and　acceleration　equations,　and　the　inverse　dynamics　model　were　set　up　for　the　analysis.　The　relationship　between　the　dimensional　parameters　and　the　input　and　output　acceleration　were　analyzed　based　on　the　manipulator　characteristics　for　a　given　velocity　and　acceleration　curve.　The　optimized　dimensions　for　the　desired　acceleration　and　required　workspace　are　given　with　a　design　example　to　prove　the　feasibility.