The polymerization of 4, 4-bis(acetoxymethyl)-1, 6-heptadiyne (BAH) was carried out by MoCl5 and WCl6 with various organometallic cocatalysts. MoCl5-based catalysts were more effective than WCl6-based ones for the cyclopolymerization of BAH. Poly(BAH) was characterized to have polymer backbone with conjugated double bond and cyclic structure by IR, UV-visible, and 1H-and 13C NMR spectroscopies. The polymer was stable up to 310 ℃ and 5 % weight loss show up at 350 ℃. The resulting dark violet polymer exhibited good solubility in common organic solvents and could be cast on a glass plate to give film with good mechanical properties. It was found that oxygen permeability (PO2) and permselectivity (PO2/PN2) of the resulting polymer were 15.2 barrer and 2.84, respectively.