The　cooperation　system　of　flexible　robots　manipulating　constrained　objects　is　a　very　complicated　and　challenging　problem　in　the　study　of　robotics.　In　this　paper,　the　dynamic　model　of　the　system　is　developed　in　the　absolute　coordinates.　The　kinematic　and　dynamic　constraints　among　the　manipulators,　object,　and　working　surface　are　included　in　the　dynamic　equation　of　the　system.　Dynamic　analyses　of　the　system　are　presented　to　determine　the　motion　of　object　and　the　input　of　robot　for　a　desired　task.　The　effectiveness　and　advantages　of　the　method　proposed　in　the　paper　are　illustrated　in　a　numerical　simulation　of　two　planar　3R　flexible　robot　arms　manipulating　a　constrained　rigid　object.