Polybutadienes were synthesized with η5-pentamethycyclopentadienyltri group titanium[Cp* TiL3

L=chloride

benzyloxy

p-methoxyphenoxy] in the presence of methylaluminoxane (MAO)．The influences of polymerization temperature [Tp]

catalyst concentration [Ti] and AlMAO／Ti molar ratio on butadiene polymerization have been studied．The external addition of triisobutylaluminum (TIBA) into the catalyst system gave a great promotion on the catalytic activity and the molecular weight of polybutadienes．The results showed that the best polymerization conditions with Cp* Ti(OBz)3／MAO as the catalytical system were [Ti] =1×10-3 mol／L

Tp=60℃

AlMAO/Ti=400(mol／mol) and AlTIBA/Ti=100．The oxidation states of active titanium centers ln Cp* Ti(OBz)3／MAO catalytic system have been determined by the redox titration method．It seems that the active center of Ti(Ⅲ) is favourable for butadiene polymerization with higher catalytic activity．