The synthesis, characterization and physical properties of energetic azido binders were discussed. The energetic composites of glycidyl azide polymer (GAP)/nitroplasticizers and polyethylene glycol with HMX in various particle sizes were studied and compared with hydroxy terminated polybutadiene (HTPB) composites. The particle size of the oxidizer played an important role in determining the performance of the propellants. It was found that the flame structure of the GAP propellants was altered by the nature of the oxidizers.