The　truss　element　is　described　according　to　the　structural　composition　characteristics　of　the　ring-shaped　supported　truss,　and　the　deformation　assumptions　are　given.　The　equivalent　polygon　structure　of　the　ring-shaped　truss　is　obtained　based　on　the　beam　model.　The　kinetic　energy　and　strain　energy　of　the　equivalent　polygon　unit　and　its　corresponding　circumscribed　circular　ring　unit　are　calculated.　The　relational　expressions　between　the　elasticity　modulus　and　density　of　the　equivalent　polygon　structure　and　the　circumscribed　circular　ring　are　derived　by　using　the　energy　equivalence　principle.　Thus,　the　expressions　of　the　frequency　ratio　are　obtained.　The　modal　shapes　and　frequencies　of　the　equivalent　polygon　structure　and　the　corresponding　ring　structure　are　compared　by　using　the　finite　element　method　and　the　theoretical　method.　The　results　show　that　it　is　reasonable　to　use　the　continuum　ring　model　to　simplify　the　equivalent　polygon　structure　for　the　dynamic　analysis　of　the　ring　truss　structure　when　the　number　of　elements　is　more　than　30.　©　2022,　Editorial　Board　of　Journal　of　Vibration　Engineering.　All　right　reserved.