Metal--organic　frameworks　(MOFs),　a　new　type　of　porous　crystalline　material,　hold　great　potential　in　biomedical　applications,　such　as　drug　delivery.　However,　the　efficacy　of　drug　delivery　is　limited　by　low　drug　loading.　In　this　work,　we　synthesized　hollow　mesoporous　silica　(HMS)@MOF　capsules　that　can　be　used　as　a　pH-responsive　drug　delivery　system　for　the　anticancer　drug　doxorubicin　(DOX).　DOX　is　loaded　into　the　inner　cavity　of　HMS.　Zeolitic　imidazolate　framework-8　(ZIF-8)　nanoparticles　are　then　coated　on　the　outer　surface　of　the　DOX-loaded　HMS.　The　obtained　material　is　a　capsule　(denoted　as　DOX/HMS@ZIF),　in　which　DOX　is　encapsulated.　The　DOX/HMS@ZIF　can　be　used　as　an　efficient　pH-responsive　drug　delivery　system.　DOX　is　not　released　under　physiological　conditions　(pH7.4),　but　is　released　at　low　pH　(4-6)　from　DOX/HMS@ZIF.　The　DOX/HMS@ZIF　capsule　shows　much　higher　cytotoxicity　than　free　DOX　and　alters　the　delivery　pathway　for　DOX　in　cancer　cells,　while　the　drug-free　HMS@ZIF　shows　excellent　biocompatibility.　This　opens　new　opportunities　to　construct　a　safe　and　efficient　delivery　system　for　targeted　molecules　using　pH-responsive　release　for　a　wide　range　of　applications.