In the study of ring-opening polymerization of vinylcyclopropanes, 1-(2-phenylcyclopropyl)-2-vinylcyclopropane(PC-VCP) which is homotriene system of biscyclopropane was prepared and its polymerization behavior was investigated. Polymerization of PC-VCP was carried out with radical initiators and photo initiator under various condition. PC-VCP polymerized in high conversion with DTBP at 120℃, and in rather low conversion with AIBN and BPO at lower temperatures. However, it failed to polymerize by benzoin methyl ether as photo initiator in 300nm UV radiation. The characterization of the polymer structure by $^1H$-NMR, $^{13}C$-NMR and IR specta indicated that the polymerization proceeded in mixed mode of 1,2-, 1,5-and 1,8-type. The polymerization mode was very much affected by the temperature. When performed at the low temperature, the reaction proceeded in high degree of double ring-opening.
