Abstract: The climatic conditions of high temperature and humidity in southern China contribute to the outbreak of cucumber blight, which is a serious threat to cucumber production. Cucumber blight pathogens from main producing areas of cucumber in Guangdong are isolated and identified to make clear the pathogen(s) of cucumber blight in Guangdong areas, and then, the pathogenicity on different melon vegetables, which is an experimental basis for melon blight disease prevention and control. Eight isolates collected from stems or leaves of infectious different cucumber cultivars planted in cucumber main producing areas of Guangdong were analyzed by morphologic observation and ITS sequence alignment and the results showed these isolates were identified as Phytophthora melonis Katsura. Under artificial inoculation, Phytophthora melonis Katsura identified exhibited certain differences in the pathogenicity on other cucurbits such as Cucurbita maxima, chieh-qua, Benincasa hispida and Luffa cylindrical, among them, Luffa cylindrical showed the highest resistance against Phytophthora melonis Katsura. The results are important for melon blight disease control and and resistance breeding in the future.