Cu nanoparticles were prepared by solution-reduction method and Cu/CNTs(carbon nanotube) composite particles were prepared by CVD (Chemical Vapour Deposition) method. The nanoparticles were characterized by SEM,TEM,XRD and FT-IR. DTA was employed to test the catalytic effects of these nanoparticles on thermal decomposition of AP. The results indicated that Cu nanoparticles made the peak temperature of high temperature decomposition of AP decrease 130.2 ℃ and the peak temperature of low temperature decomposition of AP decrease 35.1 ℃,Whereas Cu/CNTs composite particles made the peak temperature of high temperature decomposition of AP decrease 126.9 ℃，and the peaks of low and high temperature decomposition of AP overlap,proving that CNTs promote the catalytic effect of Cu nanoparticles on the thermal decomposition of AP.