Abstract: The objectives of this work were to compare and analyze the antibacterial activity between strain HD-103 and strain HD-109 and the stability of fermentation broth of the two actinomycetes against pathogenic fungi in vitro, and to identify their taxonomic status. 13 kinds of plant pathogenic fungus were used as target microorganisms, antifungal spectrums of the two strains against target fungus were determined by measuring the diameter of inhibition zone. The thermostability, pH stability and UV resistance of fermentation broth of the two strains were detected and compared through cylinder plate method, and multiple classification method was used to clarify and define their taxonomic position. The experiment results showed that the two strains had broad anti-fungal spectrum for their inhibiting growth of 10 pathogenic fungus, wherein strain HD-103 had the best activity of inhibiting Fusarium graminearum f. sp. glycines, the diameter of inhibition zone reached 23.7 mm; strain HD-109 had the best activity against Alternaria alternata, the diameter of inhibition zone reached 25.0 mm. The antimicrobial active substances produced by strain HD-103 were more stable than that of strain HD- 109. Evaluation results of taxonomy showed that HD- 103 and HD- 109 should belong to Streptomyces albidoflavus, and probably were two different variants of S. albidoflavus. The two strains of Streptomyces albidoflavus had great disease suppression effects in vitro, therefore they could be developed as a potential biological control agent against plant fungal pathogens, and had great value of application.