Abstract: Taking muskmelon bacterial fruit spot disease leaves collected from Datong district, Daqing city, Heilongjiang Province and 22 muskmelon materials preserved in the laboratory as test materials, the main pathogenic bacterial strains causing bacterial fruit spot disease in thin-skinned muskmelon in Datong District were studied by the methods of isolation and purification, morphological identification, pathogenicity identification, molecular identification, and disease resistance identification of pathogenic bacteria.The resistance performance of muskmelon materials preserved in the laboratory to this strain was also studied, in order to provide reference for the prevention and control of bacterial fruit spot disease in muskmelon.The results showed that one bacterial fruit spot pathogen was obtained from the leaves of diseased plants by isolation and purification, named HLJ23.The pathogenesis of this strain after inoculation into healthy leaves was similar to that of BFB.Further molecular identification was determined to be a subgroup I strain of Acidovorax citrulli.Among the 22 melon materials preserved in the laboratory, there were more susceptible materials than disease-resistant materials, of which 8 were resistant and 14 were susceptible.In summary, ‘1185’ and ‘258’ were the dominant population of bacterial fruit spot pathogen in thin-skinned muskmelon in Datong District, Daqing City, Heilongjiang Province.