Nonlinear　aeroelastic　characteristics　of　sandwich　beams　with　pyramidal　lattice　core　are　investigated,　and　the　active　flutter　control　of　the　nonlinear　structural　system　is　also　studied　using　the　piezoelectric　actuator/sensor　pair.　In　the　structural　modeling,　Reddy＇s　third-order　shear　deformation　theory　is　applied.　Aerodynamic　pressure　is　evaluated　by　the　supersonic　piston　theory.　Hamilton＇s　principle　and　the　assumed　mode　method　are　used　to　derive　the　equation　of　motion.　The　proportional　feedback　and　the　optimal　H　(a)　control　methods　are　performed　to　design　the　controller.　In　the　robust　control,　the　uncertainty　caused　by　omitting　the　nonlinear　terms　of　the　control　equation　is　taken　into　account,　and　the　mixed　sensitivity　method　is　used　to　solve　the　problem.　The　nonlinear　aeroelastic　property　of　the　sandwich　beam　is　analyzed　and　is　compared　with　that　of　the　equivalent　isotropic　beam　with　the　same　weight　to　show　the　superior　aeroelastic　characteristics　of　the　lattice　sandwich　beam.　Controlled　vibration　responses　under　the　two　different　controllers　are　calculated　and　compared.　Simulation　results　show　that　the　robust　controller　is　much　more　effective　than　the　proportional　feedback　controller　in　the　flutter　suppression　of　the　nonlinear　sandwich　beam.