Abstract: Few fungal insecticides against the lesser green leafhopper, Empoasca vitis, one of the most important tea tree pests in China, were applied in spite of their potential for distinctive invasion pattern. In this paper, wettable powder of a highly virulent strain Isaria javanica isolated from the leafhopper was developed with normal conidial viability and optimal physical properties. The carrier sepiolite was screened from 4 inert carriers, which got wet 3－5 s soon after being immersed into water. Wetting agent A screened from 12 agents could be wetted in 3 seconds. Dispersant B got suspension rate up to 94.9%. UV protestant fluorescent sodium had protection rate up to 76.2%. The final formulation was conidial powder (10¹¹ spores/g) 10%, wetting agent A 3%, dispersant B 5%, fluorescent sodium 1%, antioxidant C 0.5%, with carrier sepiolite added up to 100%. The germination rate of the conidia in the preparation was 55.7% after 7 months storage at room temperature, extremely significantly higher than the unformulated conidia (4.9%). The bioassay results showed that the mortality of this preparation to leafhoppers was up to 100%.