Polynorbornene was synthesized by beta-diketonate titanium / MAO (methylaluminoxane) catalysts. The polymerization activity was up to 8 x 10(3) g polymer/(mol Ti h). FT-IR, H-1 NMR, C-13 NMR and WAXD analyses showed that the polynorbornenes contained both ring-opening metathesis (trans and cis) and addition polymer chain structures and they are amorphous. The portions of trans- and cis- double bonds decreased when the polymerization temperature and Al/Ti molar ratio decreased. In addition, using 1,2-dichlorobenzene, instead of toluene, as the polymerization solvent increased the activity and produced the polymer containing more cis-double bonds. The glass transition temperature of the elastic polymers ranged from 330degreesC similar to 400degreesC.