The　primary　goal　of　this　research　is　dynamics　modeling　and　frequency　analysis　of　a　3-RRS　spatial　parallel　manipulator　with　flexible　links.　Firstly,　a　new　model　of　spatial　flexible　beam　element　was　proposed.　Then,　the　dynamics　equations　of　all　serial　sub-chains　of　the　parallel　manipulator　were　derived　based　on　the　finite　element　theory,　kineto　elastodynamics　(KED)　analysis　method　and　Lagrange　equations.　The　dynamics　model　of　the　complete　system　was　obtained　through　the　application　of　constraint　conditions　of　the　legs　and　the　movable　platform.　Based　on　the　dynamics　model,　the　relation　of　the　natural　frequencies　and　design　parameters　of　this　mechanism　were　studied　through　numerical　simulation.　From　the　simulation　results,　the　natural　frequencies　are　relatively　sensitive　to　the　sectional　parameters,　structure　size　and　characteristic　parameters　of　material　on　mechanisms.