To improve the wettability and the suspensibility of bacillus methylotrophicus wettable powder（ WP ）, the formulation of bacillus methylotrophicus WP was optimized by additives screening and orthogonal experiment. The results show that the compound adjuvant which is composed by NNO as dispersant and CB-102 as wetting agent can improve the suspensibility and wetting effects. Orthogonal experiment design was used to determine the optimum mixture proportion of the adjuvants in WP: 1% of light calcium carbonate（ LCC ）, 6% of CB-102and 6% of NNO. Based on the formulation,the suspensibility of WP can reach to 74.7%, wetting time is 48.2 s and pH value is 6.89, the index all satisfy the proper standard. The results of field experiment show that the control efficacy of bacillus methylotrophicus WP dilute 500 times and 800 times on cucumber gray mold are 78.8% and 74.7% respectively.
