Abstract: High active catalyst system for polymerization of butadiene may be obtained by combining MoCl4OR and proper aluminum alkyl. The conversion of 80% of butadiene can be achieved with 5×10-5 mole of MoCl4OC8H17 per 1 mole of butadiene at 70℃ in hydrogenated gasoline. The polydispersity of the polymer in the range of 1.5-2.0 is carried out with the temperature of polymerization at 30-70℃. For the purpose of regulating molecular weight and chain structure of the polymer allyl halides (allyl iodide) is satisfactory. With the increase of amount of allyl iodide, the molecular weight of the polymer decreases, the content of 1,2-units increases and the regularity of chain structure of the polymer rises. Some of the physical properties of the polymer are as follows: the content of 1,2-unit, 88-97%, limiting viscosity number 1.8-6.2(30℃, toluene), glass temperature, -27--10℃, tensile yield strength, 6.5-8.5 (kg/cm2), ultimate tensile strength, 12-25 (kg/cm2) and elongation at break, 1700-2900%.