To reduce the mechanical sensitivity of RDX and improve its thermal decomposition performance, three kinds of RDX/Al/SiO₂ nano-composite energetic materials of RDX/Al mass fraction as 30%, 50% and 70% respectively (the mass ratio of RDX to Al is 6:1) were prepared by sol-gel method using tetramethoxysilane as precursor and fluorine boric acid as catalyst. Their morphology and structurre were characterized by scanning electron microscopy(SEM), energy dispersive spectrometer(EDS) and X-ray diffraction(XRD). Thermal performances of the samples were investigated by thermogravimetric analysis(TG) and differential scanning calorimetry(DSC). The mechanical sensitivity of the samples was measured according to GJB772A-1997 method. The results show that the RDX/Al/SiO₂ is the nano-composite energetic material formed by the Al and RDX into the skeletonn of gel as SiO₂. The minimum particle size of RDX in composite material is 65.09 nm, with increasing the RDX-Al content, its average particle size increases.When the mass fraction of RDX-Al is 30%, compared with the pure RDX, the decomposition temperature of RDX in the composite material decreases by 22.4 ℃, compared with the raw material RDX, the characteristic drop height (H₅₀) of the sample increases by 108.6 cm and the percentage of explosion decreases by 60%.