The catalytic effects of superfine transition metal oxides Fe₂O₃, CuO and Co₂O₃ on the thermal decomposition of ammonium perchlorate was studied by differential thermal analysis. Results show that both the single transition metal oxide and the composite ones have catalytic effects on the thermal decomposition of AP (Co₂O₃>CuO>Fe₂O₃ and Fe₂O₃/Co₂O₃>CuO/Co₂O₃>Fe₂O₃/CuO in sequence), and the catalytic behavior of the composite transition metal oxides (TMOs) showed three cooperative effects, which depended on the combination and suitable mixing proportion of TMOs. From the curves of the temperature change of the higher exothermic peak of AP decomposition with the content of one of the composite TMOs, the optimum combination (Fe₂O₃∶Co₂O₃ =1∶3)can be found.