Abstract: To develop a technique for the quick detection of Ralstonia solanacearum of Peanut,a nested PCR was established.Bacterial universal primer pair L1/L2,based on the intergenic transcribed spacer(ITS)region of 16S-23 S ribosomal DNA of bacteria,was used as the first round primers and the PCR products were cloned and sequenced.A pair of special PCR primers W1/W2 was designed as the second round primers.The prime pair could amplify a single 374 bp band from genomic DNA of Ralstonia solanacearum in peanut,but not from other bacteria.The sensibility of nested PCR reached 10fg·μL-1 of DNA,1 000 times higher than that of a sample PCR.Using nested PCR assay,the pathogen could be specifically detected from infected peanut plants with or without disease symptom.