Branched glycidyl azide polymer (B-GAP) can be used to improve the rheologic characteristics and mechanical properties of solid propellants and plastic-bonded explosives. B-GAP was prepared by reaction of polyepichlarohydrin (PECH) and its monomer (ECH) with sodium azide (NaN₃) in dimethylforamide (DMF) under 70～100℃ temperature,ethylene glycol (EG) was used as an initiator of polymerization. The main factors influencing on branching and azidation were experimentally investigated,including the method to control the hydroxyfunctionality,molecular weight and its distribution.