Abstract: The mutant T2135 inserted by Tn5-lacZ is a polar mutant of Ralstonia solanacearum T2015 isolated from peanut. Modern molecular biology experimental technique was used to construct the expression plasmid pGX6191 of ORF2 at first and biological proof was carried out, then the expression plasmid pGX6191 was mated into the polar mutant T2135 by tri-parent,and pathogenic relevant gene ORF3's mutant T2135/R was obtained.