The relation between the degree of polymerization and the type of initiation as well as the relation between the polymerization degree and the chain transfer for butadiene polymerization under molybdenum and iron catalyst systems were studied. Time graph was suggested to be used to determine the type of initiation if there exists chain transfer reaction. For slowly-initiated non-steady state polymerization

it was proposed that the main chain transfer be decided in the quasisteady state period. Identical results were obtained by using graphical integra-tion and the ratios of equal rates methods to deal with the adta. Theoretical analysis was presen-red to provide the feasibility of the ratios of equal rates method.