The invention discloses streptomyces katrae NB 20, as well as a culture method and an application thereof. The strain with a preservation number of CGMCC No.5382 is preserved in China General Microbiological Culture Collection Center on October 24, 2011. Researches prove that: the strain has strong inhibition effects to colletotrichum musae, pyricularia grisea, fusarium graminearum, fusarium oxysporum f.sp.cubense, peronophythora litchi, ustilago scitaminea, fulvia fulva, xanthomonas oryzae and xanthomonas oryzae pv.oryzicola, is a broad-spectrum antagonistic strain, can be used for prevention and control of various plant diseases, has a particular good prevention and control effect to the colletotrichum musae, has the advantages of harmlessness to human and livestock, greenness and safety, good environment compatibility, difficult resistance generation and the like, and has a wide application prospect.