A multiplex PCR assay was established for rapid and accurate detection of three potato pathogens, Phytoph-thora infestans, Rhizoctonia solani and Alternaria solani. According to the published gene sequences of these three patho-gens in GenBank, we designed 3 pairs of specific primers. The main factors influencing the multiplex PCR efficiency, such as annealing temperature and primer concentration, were optimized. The results showed that our proposed multiplex PCR as-say provided high sensitivity and extraordinary speci.city. The detection limit was estimated to be approximately 40.0 fg/μL. With its high e.ciency, low cost and rapidity, the multiplex PCR assay has great potential application in the early prevention, diagnosis and control of potato diseases.