The ultrafine particles of copper chromite were prepared by LG mixing grinder through chosing technical parameters. Under the special striking and pressing,ultrafine ammonium perchlorate (AP)-copper chromite composite was made in the grinder cavity. With particles composited the interface of the two kinds of particles is increased,the dispersivity and homogenization of the particles are raised therefrom. The experimental results indicate that the catalyst effect of copper chromite is improved,and the decomposition temperature of AP is decreased. Employing the composite particles in composite propellant can increase its combustion rate.