A bacterial strain with antifungal activity against seven crop pathogenic fungi was isolated from soil and named as IIR21.The IIR21 strain was detected through agar block method and the results indicated that the IIR21 strain exhibited much stronger antifungal activity against Magnaporthe grisea,Rhizoctonia solani,Botrytis cinerea,Fusarium aminearum and Fusarium culmorum．The IIR21 strain was identified as Streptomyces through physiological and biochemical characteristics and alignment analysis of the 16S rRNA gene sequence.The fermentation broth of the IIR21 strain was separated and purificated by extraction,silica gel column chromatography and preparative high performance liquid chromatography,and a compound with a purity of 90.34% with activity against the Magnaporthe grisea 168 strain was obtained.The Streptomyces sp. IIR21 genome was sequenced using high throughput sequencing technology,and analyzed by bioinformatics tools.The result suggested that the IIR21 strain contained the gene cluster of clavams,and the metabolic pathway for clavam biosynthesis was proposed.