In order to clarify the pathogen causing the leaf spots of Prunus salicina, tissue isolation was performed to isolate and purify the pathogen, which was further identified by morphological characteristics and polygenic joint sequence analysis. The pathogenicity of the pathogen was determined by spore spraying method and acupuncture inoculation method, and 24 fungicides were screened indoors. The results showed that 4 fungal strains with the same morphological characteristics were isolated from the diseased Prunus salicina leaves. The representative strain LY12 had round colonies and white to light yellow hyphae; and had spherical, black pycnidium, with conidia colorless, monospore, mostly oval. The genes of ITS, TUB2 and LSU were used to construct the phylogenetic tree. The results showed that strain LY12 and Didymella bellidis were clustered in the same branch. According to morphological characteristics and phylogenetic analysis, strain LY12 was identified as Didymella bellidis. The pathogenicity test showed that the pathogen strain LY12 could infect the leaves, branches and fruits of plum varieties in Sichuan and Chongqing, including Qingcuili, Banbianhong, Qingnai, Jincuili, and Cuihongli, and the largest lesions appeared on the leaves. The pathogen could also infect leaves and fruits of citrus varieties including Ulick lemon, Ehime 38, and Taroko blood orange. Indoor fungicides screening test showed out of the 24 fungicides, 11 kinds of fungicides, such as 50% boscalid water dispersible granule, 38% boscalid?pyraclostrobin suspending agent, 25% azoxystrobin suspension, 75% trifloxystrobin?tebuconazole water dispersible granule ect., showed strong inhibitory effect on pathogen strain LY12. And 50% boscalid water dispersible granule had the most obvious inhibitory effect, with EC50 being 0.153 1 μg/mL.