In order to protect the activity of aluminum powder in solid rocket propellants and increase the compatibility between the superfine aluminum powder and the other compositions of solid propellants, the superfine aluminum powder with activated surface and particle size about 2 μ m were coated using hydroxyl-terminated polybutadiene (HTPB) as coating agent and isophorone diisocyanate (IPDI) as curing agent. Al/HTPB energetic composite particles were prepared. Effects of Al powder modified by silane coupling agent KH-550 and coating quantity on the morphology and composite particle size of coated aluminum powder were investigated. Composite particles were characterized by SEM, TEM, XRD, FTIR, laser particle size analyzer, TG-DTA. Results show that when the superfine aluminum powders are modified by silane coupling agent and the coating quantity of HTPB is 1.5%, the coating film of the ultrafine composite particles of Al/HTPB are homogeneous, meanwhile the energetic composite particles are spherical with core-shell structures. The coating film of HTPB can prevent the oxidation of aluminum before 400 ℃ and burn quickly and release coated active aluminum between 400~525 ℃.