With the help of the scanning electron microscope, the superfine powders produced from 8 kinds of materials by Jet Mill were experimentally investigated and were qualitatively analyzed based on the stress wave theory and the crystallography theory. It was found that the crystal structure had a decisive influence on the shape of particles, and the shape of non-crystal particles occurred at random. The particle materials produced from intensive impulsive loading maintained their original properties. The unbalanced crack extension, which caused by the defects of materials or other factors, was the main factor of material destruction.