The polybutadiene (cis-1

4 and 1

2) polymerized with iron catalyst was investigated by 18C-NMR. Assignments have been made on the spectra for all peaks of the Aliphatic and olefinic carbons using chemical shift corrective terms together with furukawa parameters. The relative intensities of peaks were calculated from the ber-noulli distribution of cis-1

4 and 1

2 units.Quantification of cis-1

4 and 1

2 contents

sequence distribution

alternation pattern of cis-1

4 and 1

2 units

and the chain propagation mechanism were discussed as a result of the detailed stdy of the spectra.