Azido-terminated hyperbranched multi-arm copolymer (POGA) with hyperbranched polyether core (PEHO-c) and linear azido-terminated glycidyl azide polymer arms (GAPA-a) has been prepared. The structures of the polymers were characterized by FT-IR, NMR, GPC and elemental analysis. The molecular weight of POGA was up to ca 17000 g mol(-1), far higher than that of common plasticizers (200 similar to 1000 g mol(-1)). The enthalpy of formation and high nitrogen content of POGA demonstrated its remarkable energy level, and low impact and friction sensitivities indicated its good safety performance in mechanical stimuli. The results of the kinetic and thermodynamic parameters, calculated from non-isothermal DSC, denoted a fine thermal stability of POGA. Furthermore, the plasticizing effect of POGA, evaluated by plasticizer efficiency and viscosity, was superior to A3 but inferior to Bu-NENA, however, its exudation was much slower than that of small molecular plasticizers, especially Bu-NENA. Moreover, the plasticizing mechanism of POGA as energetic macromolecular plasticizer was established by analyzing its structure and performance characteristics.