To improve the catalytic effect of nano-CuO, the CuO/PG nanocomposites of CuO morphology as flakes, lines, rods and spheres were prepared by complex precipitation method using porous graphene (PG) as carrier. The effect of CuO/PG nanocomposites on the thermal decomposition of ammonium perchlorate(AP) was investigated by DSC and its catalytic mechanism was analyzed. Results show that compared with the nano-CuO with the same morphology, the CuO/PG nanocomposites have larger specific surface area and better catalytic effect on the thermal decomposition of AP. Among four kinds of CuO/PG nanocomposites, the spherical copper oxide has the smallest particle size, about 4 nm and the specific surface area of the composite is the largest, about 115.25 m²·g^-1. Therefore, it has the most active catalytic sites and the best catalytic effect on the thermal decomposition of AP, so that the high temperature exothermic decomposition peak temperature of AP decreases to 310.1 ℃.