Abstract: OBJECTIVE To design and prepare a tumor-targeted pH-sensitive delivery system based on heat shock proteins(HSP) nanocages, and to evaluate its physicochemical properties. METHODS Using HSP as the matrix, which were prepared by total gene synthesis and protein recombination expression technology, HSP nanocages modified with cell-penetrating peptides Tat and PEG(PT-HSP) were produced via the functionalization of surface groups. Morphology was examined by TEM, particle size and Zeta potential were determined by nanometer particle size and zeta potential measuring instrument. Encapsulation efficiency and loading capacity were determined by HPLC. The in vitro release behavior of paclitaxel-loaded PT-HSP under pH 7.4 and pH 6.5 was investigated. RESULTS Morphological results showed that PT-HSP presented uniform spherical with a typical two-layer structure, the average size of PT-HSP was (154.4±23.6)nm, Zeta potential was (−2.6±0.7)mV. Encapsulation efficiency and loading capacity of PT-HSP detected by HPLC were (75.3±3.6)% and (7.0±0.2)%. The results of in vitro release test showed that the release rate of PT-HSP at pH 6.5 was faster than pH 7.4(P<0.01). CONCLUSION The pH-sensitive intelligent HSP nanocages drug delivery system constructed in this study, is expected to become a safe, effective and intelligent antitumor drug delivery carriers by its high loading capacity, good stability and intelligent tumor-targeting.