Abstract: In this paper, the microspheres in fly ash are used as sensitizer and inert additive to prepare the low detonation velocity emulsion explosives. The detonation velocity and the peak pressure of the air explosion shock of emulsion explosives wave were measured by the probe method, the lead column compression method and the air explosion method, respectively, and the safety of emulsion explosives was tested by the storage life experiment and thermal analysis experiment. The experimental results show that the detonation velocity, the brisance and the peak pressure of shock wave of emulsion explosives increased first and then decreased with the increase of the content of fly ash microspheres. When the content of fly ash microspheres was 15%, the detonation performance of emulsion explosive was the best, and when the content of fly ash microspheres was 45% , the detonation velocity of the explosive decreased obviously, and the detonation velocity ranged from 2191 to 2312 m·s-1, which can satisfy the use condition of explosive for explosive welding. In addition, it is found that the detonation performance of emulsion explosives with D50=79 μm fly ash microspheres was higher than those of fly ash microspheres with D50=116 μm and 47 μm. The storage life and thermal analysis results show that the storage life of low detonation velocity emulsion explosives with fly ash microspheres is significantly better than that of traditional low detonation velocity emulsion explosive with clay particles, the activation energy of thermal decomposition of the emulsion explosive with 15% fly ash microspheres was only 0.3% higher than that of emulsion matrix, and the results showed that the addition of fly ash microspheres had no obvious effect on the thermal stability of the emulsion matrix. The research results have important reference value for green resource disposal of coal-based solid waste and formulation design of the low detonation velocity emulsion explosive.