A MgCl2/AlCl3-supported Ziegler-Natta catalyst is prepared and low isotactic polypropylene is synthesized using this catalyst in the paper. The results indicate that the polymerization activity of the MgCl2/AlCl3 -supported Ziegler-Natta catalyst is much higher than that of the MgCl2-supported Ziegler-Natta catalyst. And the attenuation curves of the polymerization rate of different Al/Ti molar ratios suggest the double metal active center is more stable than the single metal active center. Also the effects of the AlCl3/MgCl2 molar ratio, polymerization temperature and external electron donor on the polymerization activity and isotactic index of the products are studied in detail. (c) 2005 Published by Elsevier B.V.