With trimethyl，4-dodecylbenezyl ammonium chloride and 18-crown-6 as pase-transfer catalysts,the azidation of polyepichlorohydrin (PECH) in poly(ethylene glycol diol)(PEG) and H₂O were studied.The reaction discipline and mechanism were discussed. The results show that the system with trimethyl，4-dodecylbenezyl ammonium chloride as phase transfer catalyst and PEG as medium is a safe and effective approach to glycidyl azide polymer (GAP) preparation,and azidational ratio of PECH can reach 97% above within 15 h.