627 strains of Actinomyces were separated from the eastern part mountainous area in Fushun Liaoning by platescreening, and antagonism in agar plate, fermented liquid and its antagonistic effect were all investigated. The results indicate that YYHS-2 showed strongly antagonistic effect against Staphylococcus aureus, Bacillius subtilis, Escherichia coli and Streptococcus mutans. The morphological, culture, physiological and biochemical characteristics of YYHS-2 all met the requirements of the definition of Streptomyces in Yan Xun-chu's taxonomy system，it's obvious that YYHS-2 belongs to Streptomyces.