To enhance the chemotherapy effect to MDA-MB-231, a glutathione (GSH)-sensitive amphiphilic hyperbranched poly (amide-amine) (mPEG-PLGA-HPAA) was synthesized, and the anti-cancer drug, paclitaxel (PTX) was then encapsulated into the mPEG-PLGA-HPAA micelles. The mPEG-PLGA-HPAA containing a large number of disulfide bonds could degrade and then consume the GSH intracellularly, which was expected to enhances the sensitivity of MDA-MB-231 cells to PTX. It was found that the mPEG-PLGA-HPAA/PTX nanoparticles could respond to the GSH and showed a GSH-controlled PTX release. Simultaneously, the mPEG-PLGA-HPAA/PTX nanoparticles significantly enhanced the efficacy of PTX by inhibiting MDA-MB-231 cells proliferation and inducing cells apoptosis, performing the self-sensitization effect of chemotherapy. Moreover, the drug carrier of mPEG-PLGA-HPAA exhibited excellent biocompatibility in vitro and in vivo. These results indicated that the self-sensitized drug carrier is a promising route to maximize the therapeutic effect and minimize the side effects of chemotherapy drugs used currently in clinical.