Abstract: High active catalyst systems for polymerization of butadiene may be obtained by combining MoCl,ORand proper aluminum alkyl.The conversion of 80% of butadiene can be achieved with 5x10~(-5) mole ofMoCl_4OC_H_(17)per mole of butadiene at 70℃in hydrogenated gasoline.The polydispersity of the polymersin the range of 1.5—2.0 is carried out with the temperature of polymerization at 30—70℃.For the purpose ofregulating molecular weight and chain structure of the polymers allyl halides is satisfactory,among othersallyl iodide is the best.With increase of amount of allyl iodide,the molecular wieght of the polymers de-crease,the 1,2-units increase and the regularity of chain structure of the polymers rises.Some of the physicalproperties of the polymers are as follows:the content of 1,2-units,88——97%;limiting viscosity number,1.8——6.2(in 30℃,toluene);glass temperature,-27——10℃:tensile yield strength,6.5——8.5(kg/cm~2);ultimate tensile strength,12——25(kg/cm~2)and elongation at break,1700—2900%.