Acetylene monomer was polymerized with vanadiUrn based catalyst to form free standing film of polyaeetylene (PA)．The effect of polymerization conditions including catalyst concentration，aging time of catalyst，polymerization solvent and temperature on morphology，catalytic activity and cis content has been investigated．It is shown that the catalytic activity of catalyst system containing VO (acac)2 is higher than that of V (aeac)3．The suitable conditions for preparing PA film：molar ratio Al／V of 4-一6；eoneentration of vanadium compounds>0.4 mole／l．When tetrahydrofuran and n-butyl ether were used as polymerization solvent，PA power Was formed．The eis content of PA film depends upon the polymerization temperature，but is not higher than 70％．The room temperature eonduetuivity of the PA film doped with It is in the range of 10一102Ω-1·cm-1，similar to that prepared with Ti (OBu)4-Am3． The conductivity of PA film obtained with catalyst system composed of V4+ was higher than that of V3+ eatalyst．The observation．by a scanning electron microscope showed that the film is composed of an accnmlation of fibrils with diameter of 1000 A．The bulk density is about 0.8g／cm3．