The polymerization of phenylacetylene at room temperature by UV laser activated W(CO)(6) in CH3I solvent was investigated. The weight-average molecular weight of the polymer is 10(3), and the H-1 NMR spectra of polymers indicate that the polyphenylacetylene has a cis-transoidal structure. The experimental data show that not only laser wavelength, energy and irradiation time influence on the yield of polymer but also the laser energy influences the structure of polymer.