According　to　the　structural　characteristics　of　space　truss　antennas,　based　on　the　principle　of　energy　equivalence,　the　equivalent　beam　continuum　models　of　space　truss　structures　without　and　with　floor　plates　are　established　respectively.　Assuming　that　the　three　displacement　components　of　the　truss　structure　have　a　linear　relationship　in　the　cross　section　plane,　that　is,　the　displacement　at　any　point　on　the　cross　section　of　the　cell　can　be　expressed　linearly　by　the　displacement　component　at　the　center　of　the　cross　section.　The　strain　energy　and　kinetic　energy　of　the　cell　can　be　obtained.　Based　on　the　energy　equivalence　principle,　the　dynamic　equation　of　equivalent　continuum　of　truss　antenna　structure　is　established　by　using　Hamiltonian　principle,　and　the　expressions　of　natural　frequency　and　mode　of　vibration　of　equivalent　continuum　model　are　obtained.　The　modal　analysis　of　truss　structure　is　carried　out　by　using　finite　element　software.　The　results　of　finite　element　simulation　are　compared　with　those　of　equivalent　continuum　model,　and　the　correctness　of　equivalent　continuum　beam　model　is　verified.　©　2023　Xi＇an　Jiaotong　University.　All　rights　reserved.