The study of the kinetics of gas phase polymerization of butadiene with heterogeneous catalyst based on. neodymium (Nd) was carried out. The effects of reaction temperature, reaction pressure, dispersing medium, and types of catalyst on kinetics of polymerization were investigated. A kinetic model with two kinds of active sites was proposed. The results allow that the effect,, of the reaction temperature and the types of dispersing medium and catalyst oil the kinetic performance of polymerization are significant, and that the combined model of first and second order decay Of active site of catalyst can be used to describe the phenomena.