Nano 2，6-diamino-3，5-dinitropyrazine-1-oxide （LLM-105） was prepared by ultrasound-assisted microfluidic technology based on the solvent and non-solvent method to improve the morphology and reduce the particle size. The microscopic morphology and crystal structures of the samples were characterized by field emission scanning electron microscopy （FE-SEM） and X-ray diffraction （XRD）. In addition， The promotion of fluid mixing by ultrasonic method was demonstrated by fluid visualization. The results showed that the spherical particles prepared by ultrasound were smaller and homogeneous， with an average particle size of 137.65 nm. Meanwhile， the crystal structures remained unchanged from the raw material. Differential scanning calorimetry （DSC） showed that the thermal decomposition temperature of nano-LLM-105 was reduced compared to the raw material， demonstrating that ultrasonic assistance can not only improve the efficiency of preparing nano-LLM-105， but also significantly reduce the particle size.