To explore the effect of solid boron hydrogen fuel on the burning mechanism of aluminum powder， the simultaneous thermal analysis-infrared mass spectrometry technology and the pyrolysis in-situ cell-Fourier transform infrared spectroscopy technology were employed. Combining with the numerical model of the effect of BHN-12 on the burning reaction of aluminum powder in the explosion flow filed， the mentioned experiment was introduced to study the reaction time， dispersion characteristics and combustion-supporting effect of boron-hydrogen fuel. Results show that the thermal decomposition process of BHN-12 started from 314 ℃， and ended at 360 ℃. There are three exothermic peaks and two endothermic peaks during the decomposition process with a total mass loss 32.3%-33.9%. The decomposition process obeyed the law of power series （Mampel power）， and the dynamic mechanism function is . The gaseous products of the thermal decomposition are mainly H₂， C₂H_4， C₂H₆ and NH₃， and the solid products are simple substances of amorphous C and B. The component transportation model was introduced to simulate the after- burning process of the Al/BHN-12 system. During the process， the dispersion speed of Al fuel was slower than that of BHN-12 particles. At the time of 20 ms， the dispersion radius of Al fuel was about 2.5 m， but it was 3m for BHN-12. In the first 2 ms of the reaction， there was no gaseous product produced， until 4m the gaseous products came out with a temperature 1800 ℃ in the middle of the fire ball. BHN-12 could increase the after-burning temperature of the entire system by about 300 ℃.