Azobenzene-terminated poly(dimethylaminoethylmethacrylate) (PDMAEMA-AZO) with pH, temperature and light triple-sensitivity was synthesized by reversible addition fragmentation chain transfer (RAFT) polymerization of dimethylaminoethylmethacrylate (DMAEMA) at present of azobenzene-containing trithiocarbonate chain transfer agent (CTA-AZO). The structure of the prepared PDMAEMA-AZO polymer was characterized by ultraviolet spectroscopy (UV), Fourier transform infrared spectroscopy (FTIR), hydrogen nuclear magnetic resonance spectroscopy (1HNMR) and gel permeation chromatography (GPC), and the properties of photo, temperature and pH-sensitivity of the polymer were investigated. The results of GPC indicate that the relative molecular weight of the as-synthesized polymers is controllable and the molecular weight distribution (PDI) is below 1.78. The photosensitivity of PDMAEMA-AZO polymer in water, ethanol and chloroform shows that PDMAEMA-AZO polymer can undergo rapid and reversible cis-trans photo-isomerization subjected to UV and visible light alternately, and quickly reach photo stable state. The thermosensitivity of PDMAEMA-AZO shows that the lower critical solution temperature (LCST) of PDMAEMA-AZO is lower than that of PDMAEMA. The LCST of polymer decreases with the increase of its concentration, and the window of the phase transition is narrowed. When the pH exceeds 9.44, the LCST of the PDMAEMA-AZO polymer remains unchanged. When the pH drops from 9.44 to 7.34, the LCST increases, and when the pH is less than 7.34, it is no longer temperature sensitive. The above thermosesitivity results indicate that the polymer was a LCST-type temperature-sensitive polymer under the control of pH. Finally, the LCST of the polymer reversibly increases and decreases subjected to multiple alternating irradiation of UV and visible light, which shows that the PDMAEMA-AZO polymer has light-controlled thermosensitivity.