Refined 3-nitro-1，2，4-triazol-5-one （NTO） product were prepared by spray drying technology to improve the morphology and reduce the particle size. Acetone was used as the experimental solvent. The effects to inlet temperature， inlet flow rate， feed rate and precursor mass concentration on the morphology and particle size of the refined NTO were investigated， and the optimal spray drying process parameters was selected. The surface morphology， molecular structure and thermal stability of refined NTO products were characterized by scanning electron microscopy （SEM）， X-ray diffraction （XRD） and fourier transform infrared spectroscopy （FT-IR）， and synchronous thermal analyzer （TG-DSC）. The results show that the sphere-like NTO with good morphological， stable crystal structure， narrow particle size distribution range and an average particle size of 1.2 μm can be obtained when the inlet temperature is 60 ℃， the inlet gas flow rate is 357 L·h^-1， the feed rate is 3 mL·min^-1， the NTO precursor concentration is 16.57 mg·mL^-1. Compared with the feedstock， the thermal decomposition activation energy of the refined NTO was enhanced by 41.7 kJ·mol^-1， and the thermal explosion critical temperature was increased by 10.4 ℃， which has better thermal stability.