In order to prevent non-specific internalization of the drug;and concomitantly enhance the physical stability and tumor target ability of poly(ethylene glycol)-poly(D, L-lactide) (PEG-PLA) micelles, two novel sets of pH-sensitive charge-reversal systems ,the cell penetrating decapeptide arginine-glycine (RG)5 and a pH-sensitive masking decapeptide histidine-glutamic acid (HE)5 ,for cell penetrating peptides (CPP) were created by conjugation to PEG-PLA micelles and evaluated by in vitro and in vivo studies.