The DMC catalyst is double metal cyanide catalyst. Compared with similar polyols made using basic(e.g., KOH)catalysts, polyether polyols made from the catalyst have low unsaturations, narrow molecular weight distributions, have high molecular weight, and are useful in making a variety of polyurethane products. DMC catalyst is highly active in epoxide polymerization reactions used to prepare polyether polyols. We can yield the DMC more than 20000 kg within one year, and thus afford to produce 50 ～ 70 ten thousand tons of polyols. This catalyst is white or light yellow powder, is suitable for preparation of polyols with 1~6 functions. Compared with basic catalysts, this catalyst can be used with less amount (30ppm), and reaction time of polymerization is reduced largely, and the polyols products are not necessary to be refined. The DMC is suitable for using in common epoxide polymerization reactors, but it can be better if reactors have both of stirring and cycling systems. When usi