A　novel　tortoise-like　flexible　micro-robot　with　four　legs　is　presented,　which　can　crawl　and　swim　underwater.　The　legs　are　actuated　by　ICPF　(Ionic　Conducting　Polymer　Film)　and　can　be　driven　by　a　low　voltage.　ICPF　is　a　kind　of　smart　films,　it　has　the　characteristics　of　flexibility　and　good　response.　For　analyzing　the　characters　of　the　robot　and　improving　the　reliability　and　feasibility,　we　establish　a　dynamic　model　of　the　micro-robot　by　applying　Pseudo-Rigid-Body-Dynamic-Model　(PRBDM).　The　model　is　established　on　the　base　of　staties　and　kinetics　by　considering　the　dynamic　effect　of　the　robot.　Then,　the　displacement　of　the　legs　of　the　micro-robot　is　investigated　based　on　PRBDM.　The　relation　between　the　displacement　of　the　robot　legs　and　the　frequency　of　the　electrical　voltage　is　theoretically　derived　from　the　PRBDM　model　and　some　analyses　and　experiment　graphs　about　the　relation　are　performed.