This　article　is　devoted　to　investigating　sound　insulation　performance　of　a　simply　supported　sandwich　plate　with　an　hourglass　lattice　core.　The　governing　equations　of　lattice　core　sandwich　plate　are　established　using　the　Reissner　sandwich　plate　theory.　The　solutions　are　derived　using　Fourier　series　expansion.　The　developed　model　is　verified　through　the　comparison　with　the　results　of　the　models　from　the　existing　literature,　as　well　as　finite　element　method　(FEM).　The　effects　of　various　structural　and　material　parameters,　the　incident　angle,　and　azimuth　angle　of　the　incident　sound　on　sound　insulation　characteristics　are　investigated.　It　is　demonstrated　that　the　sandwich　plate　with　the　hourglass　lattice　core　can　outperform　that　with　the　traditional　lattice　cores.　This　work　provides　useful　guidelines　for　the　design　of　lightweight　lattice　sandwich　structures　in　the　application　of　sound　insulation.