In this paper，polydiphenylbutadiyne (1) and phenylacetylenc-diphenylbutadiyne copolymer (2) are synthesised using (Ph₃P)₂PdCl₂ as catalyst. In the copolymerization，the best mole ratio of two monomers diphenylbutadiyne and phenylacetylene is 1/2. The catalytic homopolymerization of diphenylbutadiyne is superior to that of the thermal homopolymerization. According to infrared and ¹H-NMR spectra，the structure of polymer (l) and copolymer (2) may a11 be trans-transoidal configuration.