Strain CanL30 of Bacillus velezensis was incubated in 10L,1ton and 10ton jar fermenters for characterization of bacterial growth and endospore development. A water wettable powder of CanL30 was formulated based on the endospores from the bacterial cultures,and the powder was evaluated for efficacy in control of Sclerotinia stem rot and blackleg of oilseed rape. The results showed that CanL30 could grow and form endospores in the fermenters. After incubation at 30℃ for 48 h in the 10L fermenter,for 36 h in the 1t fermenter and for 40 h in the 10t fermenter,the endospore formation rates were 74%,93% and 92%,respectively. In the 1t and 10t fermenters,the final bacterial yield reached 1×1010 cfu/mL and 3.3×109 cfu/mL,respectively. The resulting bacterial cultures were dried by heat spray,and a water wettable bacterial powder (1×1011 cfu/g) was prepared by amending the bacterial powder with related additives. The formulated powder conforms to the national standard of wettable powder pesticides regarding the thermal stability (54℃),suspension ability and wettability. The results of the bioactivity tests on agar medium showed that the powder had the antifungal activity against mycelial growth/sclerotial formation by S. sclerotiorum,and conidial germination of L. biglobosa. The result of the indoor biocontrol assay showed that the powder effectively suppressed infection by S. sclerotiorum and L. biglobosa on leaves of oilseed rape. The result of the field biocontrol assays in Tianmen City and Chibi City of Hubei Province showed that the powder suppressed Sclerotinia stem rot and blackleg by 55% and 42%,respectively,and the efficacy were not significantly different (P>0.05) from those in the treatment of the fungicide prochloraz,which suppressed Sclerotinia stem rot by 51% and blackleg by 37%. Compared to the control treatment,the application of the CanL30 powder significantly (P<0.05) increased the yield of seeds of oilseed rape by 14% in the Tianmen trial and 12% in Chibi trial. These results suggest that the water wettable powder of CanL30 can effectively suppress Sclerotinia stem rot and blackleg of oilseed rape,and meanwhile,it can enhance the seed yield of oilseed rape.