In　the　paper,　we　present　a　novel　tortoise-like　flexible　micro-robot　with　four　legs　which　can　crawl　and　swim　underwater.　These　legs　are　actuated　by　ICPF　(Ionic　Conducting　Polymer　Film)　which　is　a　kind　of　smart　film　and　has　the　characteristics　of　flexibility,　good　response　and　being　driven　by　a　low　voltage.　For　analyzing　the　characters　of　the　robot　and　improving　the　reliability　and　feasibility　of　the　robot,　we　establish　the　dynamic　model　of　the　micro-robot　by　applying　Pseudo-Rigid-Body-Dynamic-Model　(PRBDM).　The　model　is　established　by　considering　the　dynamic　effect　of　the　robot,　which　is　based　on　statics　and　kinematics.　Then,　the　frequency　analysis　of　the　micro-robot　based　on　PRBDM　is　investigated.　Based　on　the　PRBDM,　the　relation　between　the　structure　parameters　and　the　natural　frequency　of　the　leg　is　theoretically　derived　and　some　analysis　and　experiment　graphs　about　the　angle　displacement　of　the　leg　are　performed.