[objective] There is a great deal of interest in using nanometer-sized transition metal oxide(TMO) as catalyst in the solid propellant ． The problem is that nanoparticles of TMO are easy to aggregate and cannot be distributed homogeneously in the solid propellant, which leads to a decrease in the catalytic activity. To improve the catalytic activity of nanometer-sized particles, composite processing technique was employed which changed the adding mode of catalyst TMO (CuO and Co 2 O 3 ) and the oxidizer (AP). [Methods] CuO/AP and Co 2 O 3 /AP composite nanoparticles were prepared by a novel solvent-nonsolvent method. TEM and ICP were used to characterize their morphology and composition. The effect of composite processing of TMOs and the TMOs content on their catalytic activity on the thermal decomposition of AP were researched. [Results] The TEM results show that AP covers the surface of TMO nanoparticles. Comparing with the samples of mixing pure TMO nanoparticles with AP, the peak temperature of high temperature decomposition of CuO/AP composite nanoparticles decreases 5.4 ℃ and Co 2 O 3 /AP composite nanoparticles decreases 16.27 ℃ . The optimum CuO and Co 2 O 3 added are 2 wt% and 1.5 wt% respectively. [Conclusion] The results reveal that the composite processing of TMOs and AP can improve the catalytic activity of TMOs on the thermal decomposition of AP. The larger interface between TMOs and AP and lower density of AP in TMOs/AP composite nanoparticles are responsible for the enhancement of catalytic activity of TMOs.