A gene expression cassette with molecular size of the insert, a recombinant plasmid containing the PK gene of PRV,equal to vector was cloned through partial repair of the terminal ends of insert and vector, thus transforming them from nonadherent to adherent ones. The constructed gene expression vector of PRV with the report gene was further identified by endonuclear enzyme analysis and the biological activity of expression vector was recognized directly through transfecting cells to detect its transient expression in vitro.