Abstract: Biocontrol effects of biopesticide "Shudekang" which is composed of two strains of Bacillus and one strain of Serratia on bacterial fruilt blotch (BFB) of watermelon was evaluated under greenhouse conditions through some parameters such as biocontrol efficacy, biomass, content of chlorophyll and nutritional elements in watermelon leaves. Results showed that biocontrol efficacy was 40.8% and the biomass of watermelon seedlings increased about 51.0% in the "Shudekang" treatment compared to the control. The contents of chlorophyll A, chlorophyll B, total chlorophyll and N, P, K in the leaves of watermelon seedlings were also increased in "Shudekang" treated plants, and the increase rate were 13.4%, 46.2%, 21.3% and 22.5%, 36.4%, 29.0%, respectively.