Abstract: The application of Polymerase chain reaction (PCR) for DNA amplification in vitro Possesses many advantages, such as the sensitivity, specificity, rapidness, and convenience, etc.PCR technique has been wide-spreadly applied to the fields of molecular biology, microbiology, medicine and genetics, and showed great value with broad prospects.In plant anthology, PCR technique has been applied to the diagnosis and detection for plant diseases, especially the plant virus and virus-like disease with the sensitivity of pg/fg.Moreover, it has also been applied to the identification of plant pathogenic fungi, bacteria and nematodes, as well as the cloning and sequencing of nucleic acids of plant viruses and viroids.Possible linitations and future Potentials of PCR in the application of plant Pathology were also discussed.