Abstract: To determine the taxonomic status of a fungus strain ZK-2 with biocontrol potential and its control efficacy against potato black scurf, this study conducted taxonomic identification of strain ZK-2, evaluated its antagonistic activity against various plant pathogens, and validated its actual disease-control function through pot experiments. The strain was identified based on morphological characteristics combined with ITS and β-tubulin gene sequence analyses. Its inhibitory effects against target pathogens were assessed using the dual-culture plate assay, while its control efficacy against potato black scurf and its impact on the pathogen population in soil were evaluated via pot trials. The results showed that strain ZK-2 was identified as Aspergillus sydowii. It exhibited pronounced inhibitory activity against Rhizoctonia solani, Alternaria solani, and Verticillium dahliae, with inhibition zone widths of 10.0 mm, 9.0 mm, and 16.5 mm, respectively. Pot experiments further demonstrated that treatment with ZK-2 significantly reduced the disease index of potato black scurf, achieving a control efficacy ranging from 46.6% to 61.2%, and effectively suppressed the population of R. solani in soil. These results indicate that Aspergillus sydowii ZK-2 possesses promising biocontrol potential against potato black scurf disease and holds value for development as a biocontrol agent. This study provides new resources and a theoretical basis for the green management of soil-borne diseases.