Abstract: Objective:This study investigated the relationship between marine Streptomyces sp. MCCC 1A09830 and other strains,and isolated and purified the antimicrobial active substance which was produced by Streptomyces sp. MCCC 1A09830,and identified the structure of antimicrobial active substance. Method:The relationship between Streptomyces sp. MCCC 1A09830 and other strains was investigated by constructing phylogenetic tree. Methanol extraction,silica gel column chromatography and high performance liquid chromatography were used to isolate and purify the the antimicrobial active substances,and the structure of antimicrobial active substance was identified. Results:There was a close relationship between Streptomyces sp. MCCC 1A09830 and Streptomyces sp. NEAE-126. The antimicrobial active substance produced by Streptomyces sp. MCCC 1A09830 was purified and compound 1was obtained. The structure of compound 1 was identified as Borrelidin A by Mass Spectrometry and Nuclear Magnetic Resonance. Conclusion:One antimicrobial active substance was isolated from fermentation broth of Streptomyces sp. MCCC 1A09830,which enriched the strain that produce Borrelidin and provide support for isolation of active substances produced by marine strains.