An　analytical　model　of　laminated　composite　double-plate　system　(LCDPS)　is　established,　which　efficiently　analyzes　the　common　3D　plate　structure　in　engineering　applications.　The　proposed　model　combines　the　first-order　shear　deformation　theory　(FSDT)　and　the　classical　delamination　theory,　and　then　the　LCDPS＇s　vibration　characteristics　are　investigated.　In　the　process　of　analysis,　the　improved　Fourier　series　method　(IFSM)　is　used　to　describe　the　displacement　admissible　function　of　the　LCDPS,　which　can　remove　the　potential　discontinuities　at　the　boundaries.　Five　sets　of　artificial　springs　are　introduced　to　simulate　the　elastic　boundary　constraints,　and　the　restraints　of　the　Winkler　elastic　layer　can　be　adjustable.　The　improved　Fourier　series　is　substituted　into　the　governing　equations　and　boundary　conditions;　then,　applying　the　Rayleigh-Ritz　method,　we　take　all　the　series　expansion　coefficients　as　the　generalized　coordinates.　After　that,　a　set　of　standard　linear　algebraic　equations　was　obtained.　On　this　basis,　the　natural　frequency　and　mode　shapes　of　the　LCDPS　can　be　obtained　by　solving　the　standard　eigenvalue　problem.　By　the　discussion　of　numerical　examples　and　the　comparison　with　those　of　the　reports　in　the　literature,　the　convergence　and　the　reliability　of　the　present　approach　are　validated.　Finally,　the　parametric　investigations　of　the　free　vibration　with　complex　boundary　conditions　are　carried　out,　including　the　influence　of　boundary　conditions,　lamination　scheme,　plate　geometric　parameters,　and　elastic　coefficient　between　two　plates.