Astragalus membranaceusis planted in large quantities in Moqi area of Inner Mongolia. Root rot is one of the diseases affecting the yield of A. membranaceus. In this study, the root rot of A. membranaceus in this area was used as the research object. The symptoms of the disease, tissue isolation and pathogenicity of the diseased plants were described. Four pathogens of root rot of A. membranaceus were obtained by culture characteristics, micromorphological characteristics and molecular biological techniques. The isolates LD1 were identified as Fusarium oxysporum, LD2 as F. solani, LD3 as F. acuminatum, LD4 as F. equisetim. It was first reported that LD4 caused root rot of A. membranaceus.