By Tyndall effect, the observation of electronic microscope, super|filtering experiment and determination of the electric conductivity of non|aqueous system proved that Fe(naph)-2|Al(%i%|Bu)-3| CH-2 CHCH-2Cl catalyst was a colloidal disperse system in butadiene|contained hydrogenated gasoline solvent. Catalytic activity sites were located on the surface of colloidal particles. So the catalyst was colloidal catalyst. Al(%i%|Bu)-3 existed in associated state and dissociated into ion couple. The reaction between the ion couple and Fe(naph)-2 was the chief reaction to form colloidal core. Di|%i%|butylaluminum chloride produced by the reaction between the ion couple and CH-2 CHCH-2Cl formed an active site on the surface of the core. The electric double layer yielded by a proper excess Al(%i%|Bu)-3 made the colloidal particles comparatively stable. The catalyst particles are amorphous. The ratio of catalyst components affected the shape of colloidal particles, among which the colloidal particles of the optimal ratio were small in size, even distributed and with high catalytic activity. Since the catalyst was of the coalescence unstable colloidal system, in the period of aging, the colloidal particles aggregated and grew quickly, so its activity was decreased obviously.