Submicrometer-sized 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) crystals were prepared by spray-crystallization method with dimethyl sulfoxide (DMSO) and ultra-pure water with surfactant as the solvent and anti solvent, respectively. Submicrometer-sized LLM-105 particles were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and particle size analysis. The thermal stability and sensitivity properties of submicrometer-sized LLM-105 were also investigated. The results revealed that the submicrometer-sized LLM-105 particles are spherelike in morphology with a narrow particle size distribution at the range of 100-600nm. The submicrometer-sized LLM-105 has a lower exothermic peak at about 343.7 degrees C compared with the synthesized material. Sensitivity tests showed that submicrometer-sized LLM-105 is more insensitive under impact stimulus with a drop height (H-50) of 102cm. The submicrometer-sized LLM-105-based PBX is more sensitive for short impulse shock wave that can be initiated at lower initiation current.