Using emulsion double metal cyanide (EDMC) complex instead of Lewis acids etc as catalyst the hydroxyl terminated polyepichlorohydrin (PECH) with high relative molecular mass（MW） and narrow distribution was synthesized by ring-opening polymerization of epichlorohydrin (ECH). The PECH obtained can be used to prepare energetic azide binders with top quality. The key factors influencing the ECH′s polymerization were studied,including initiators,addition method of monomer,dosage of catalysts,and reaction time. Results show that the functionality of PECH varies as types of initiators. The increase of catalyst dosage and the rise of reaction temperature result in higher MW of PECH. To add the monomer droprise continuosly could be helpful to improve the polymerization. The yield of PECH reaches more than 95% on the conditions listed below: bisphenol A as initiator, catalyst dosage of 0.05% (based on resulting PECH mass),reaction temperature of 128 ℃. The MW of PECH can be adjusted by varying the molar ratio of monomer to initiator. The functionality of the synthesized PECH was calculated based on f= (OH value/MW)/56100 and found to be of 2-3. The PECH structure was identified by FTIR, 1H NMR, and GPC.