Chemotherapy is a traditional therapeutic approach for the treatment of many solid tumors, but the poor solubility and low bioavailability of hydrophobic anti-cancer drugs greatly limit their applications. In this article, DOX-loaded micelles were fabricated based on an amphiphilic graft polymer composed of hydrophilic poly(γ-glutamic acid) (γ-PGA) and hydrophobic poly (L-lactide) (PLLA). The structure of the copolymers and the characteristic of the micelles were studied. The release profiles of doxorubicin as a model drug from the micelles were measured. Due to the protonation of the amino group of DOX and the conformational alteration of γ-PGA, the release of DOX from γ-PGA-g-PLLA micelle was faster in the acid condition, which is beneficial to tumor therapy. The cellular uptake of the DOX-loaded γ-PGA-g-PLLA micelle was proved to be a GGT-mediated process.