The principle of small-angle scattering technique to characterize energetic materials′ structure was analyzed in detail. The application of SAS technique used in energetic materials structure′s measuring was also summarized. The research indicated that SAS technique can be used to measure not only the special microstructure of explosives′ powder, but also the explosives pillar and PBX′s microstructure quantificationally. It is also very useful for characterizing ultrafine and nanometer energetic materials′ agglomerating state.