In this paper，the polyphenylacetylene(PPA) is synthesised by the polymerization of phenylacetylene with two kinds of catalysts，anhydsous AlCl₃and (Ph₃P)₂PdCl₂. Using anhydrous AlCl₃ as catalyst，the cis-trans PPA is obtained. And using (Ph₃P)₂PdCl₂,the trans-cis PPA is found. Therefore，the polymerization of phenylacetylene may follow complex catalysis mechanism when anhydrous AlCl₃ is used as a catalyst and it may follow metathesis catalysis mechanism when (Ph₃P)₂PdCl₂ is used.