The invention discloses a wettable powder of Streptomyces aureus verticalus HN6, which is prepared from the following components in mass percentage: 5%-20% of liquid fermentation product of Streptomyces aureus verticalis HN6, 1%-5% of wetting agent, dispersing 1% to 5% of the agent, 0.5% to 2% of the stabilizer, and 100% of the filler. The preparation method includes: putting wetting agent, dispersant, stabilizer and filler into the airflow mill according to the above weight to pulverize, passing through a 325-mesh sieve, and after cooling down, adding the liquid fermentation product of Streptomyces aureus verticalus HN6, and continuing pulverization, the moisture content is ≤ 5%, the number of active spores is 0.1 to 1 billion / g, which is qualified after inspection and packed for storage. Beneficial effects of the present invention: the medicament belongs to living microorganism preparation, has remarkable effect on banana wilt, has good control effect on other diseases, has no toxic and side effects on ecological environment, and can guarantee the quality and safety of agricultural products.