The precursor of CoFe₂O₄ nanoparticles was prepared by in situ chemical precipitation at the oil-water interface，and its thermal decomposition characteristics were studied by DSC. The as-prepared CoFe₂O₄ nanoparticles calcined at different temperatures were characterized by XRD and TEM，and the effects of catalysis of the CoFe₂O₄ nanoparticles with different contents on the ammonium perchlorate decomposition were studied by DSC. Results show that CoFe₂O₄ nanoparticles with spinel structure initially are formed at 300 ℃，and with the increasing of calcination temperature，the crystallization tends to be completed and the crystallite size increases gradually. The CoFe₂O₄ nanoparticles with small particle size and good crystallinity can be obtained after heat treatment at 500 ℃. Adding CoFe₂O₄ nanoparticles can remarkably decrease the high temperature decomposition peaks of AP and the catalytic effect is increased with the increasing of content of CoFe₂O₄ nanoparticles.