Stimuli-responsive polymers have undoubtedly been of great interest in the past decades due to a variety of their potential applications in biomedical territory. However, their non-degradability limits their in vivo applications. Herein, we report a novel pH and temperature dual-stimuli responsive-poly(β-amino ester). The pH/temperature sensitivities are interrelated and can be easily tuned by changing PEG-diacrylate chain length and the percentage of biamines in the feed ratio. These dual-responsive polymers are very useful in drug delivery. Reaction of methyl ether poly(ethylene glycol)(MPEG) and poly(β-amino ester) resulted in an amphiphilic MPEG-PBAE block copolymer which could form nanoparticles by selfassembly. A hydrophobic drug(DOX) was loaded in the self-assembled nanoparticles at low temperature without using organic solvents. The loaded drug was released very slowly and steadily at 37 ℃ under physiological conditions(p H 7.4), but rapidly released from the micelles in weakly acidic environments(pH 6.4 and 5.0) for intracellular drug release. Thus, these poly(β-amino ester) polymers constitute ideal drug carriers since their thermal sensitivity allows the drug loadings without using organic solvent and their pH sensitivity permits fast intracellular drug release. Yet, their non-degradability limits their in vivo applications. Herein, we report a novel pH and temperature dual-stimuli The pH / temperature sensitivities are interrelated and can be easily tuned by changing PEG-diacrylate chain length and the percentage of biamines in the feed ratio. These dual-responsive polymers are very useful in drug delivery (PEG) and poly (β-amino ester) resulted in an amphiphilic MPEG-PBAE block copolymer which could form nanoparticles by selfassembly. A hydrophobic drug (DOX) was loaded in the self-assembled The loaded at low temperature without using organic solvents. The loaded drug was released very slowly and steadily at 37 ℃ under physiological conditions (p H 7.4), but rapidly released from the micelles in we Thus, these poly (β-amino ester) polymers constitute ideal drug carriers since their thermal sensitivity allows the drug loadings without using organic solvent and their pH sensitivity permits fast intracellular drug release .