Considering the specific pH gradients of tumour microenvironments, a dual acid-responsive drug delivery system, which can respond to the tumor extracellular and intercellular pH stimuli, has been fabricated via simple host-guest recognition. Firstly, we synthesise 2,4,6-trimethoxybenzaldehyde modified dextran (Dex-TMBA) and mPEG-imine-β-cyclodextrin (PIC), respectively. And then, through the host-guest recognition between the cyclodextrin (CD) of PIC and the benzene ring of Dex-TMBA, a kind of dual acid-responsive supramolecular drug delivery system can be fabricated. Under neutral pH conditions, anticancer drugs can be loaded by forming supramolecular nanoparticles via the host-guest recognition. While, at tumor extracellular pH (∼6.8), the acid-labile benzoic-imine of PIC cleaves and the nanoparticles are amino positively charged to facilitate cell internalization. Subsequently, due to the hydrolysis of acetal bonds in Dex-TMBA under significantly increased acidity in subcellular compartments such as the endosomes (∼5.3), the loaded doxorubicin releases from the endocytosed drug delivery. This dual acid-responsive nanoparticles can efficiently load and release drugs, acting as drug delivery systems for enhancing anticancer efficiency.