The　pH-responsive　bimodal　mesoporous　SiO2　nanocomposite　(D-P/BMMs)　was　prepared　via　two-steps　method,　which　was　achieved　by　the　combination　of　pH-responsive　Dex-PAA　polymer　with　the　bimodal　mesoporous　silica　(BMMs).　The　structural　characteristics　and　textural　properties　of　the　resultant　D-P/BMMs　were　characterized　by　means　of　XRD,　SEM,　FT-IR,　TG　and　N2　adsorption-desorption　techniques,　which　demonstrated　that　the　mesoporous　ordered　degree　of　BMMs　was　decreased　because　of　coating　of　Dex-PAA　polymer.　Meanwhile,　the　pH-responsive　drug-controlled　delivery　was　systematically　investigated　by　using　ibuprofen　as　a　model　drug　under　phosphate　buffer　solutions　(PBS)　with　different　pH　values,　and　the　results　showed　that　the　releasing　yield　of　ibuprofen　was　up　to　46%　at　pH=7.4　more　than　that　at　pH=2.0　(around　26%),　suggesting　that　the　D-P/BMMs　nanocomposite　has　an　excellent　performance　of　pH-responsive　drug　delivery.