NOVELTY - A screened Bacillus subtilis XWJLSP-1 for taking corn starch sewage as a carbon source of a culture medium, where the strain is preserved in China General Microbiological Culture Collection Center (CGMCC) with a preservation number of CGMCC No. 6478, is new.    USE - The screened B. subtilis XWJLSP-1 is useful for producing a B. subtilis XWJLSP-1 wettable powder (claimed).    ADVANTAGE - The method overcomes the deficiency of the existing technology, it not only reduces the production cost, but also achieves the purpose of environmental protection. The produced product probiotic activity is high, safe and reliable.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are: (1) a method of screening B. subtilis XWJLSP-1 applicable to taking corn starch sewage as a carbon source of a culture medium, comprises: (a) obtaining culture medium: (i) enriching a liquid culture medium: corn starch sewage process, 10-15% of corn pulp, 1-15% (w/w) of sodium chloride (NaCl) 10.0 g/L, calcium carbonate powder 10-50 g/L, the pH value is 7.0-7.2, (ii) separating culture medium comprising 2% of agar enriched with a liquid culture medium; (b) separating a strain: (i) taking soil solution boiling for 1-30 minutes, then taking 100 mu l added with enriched liquid culture medium, shaking culture for 15-20 hours, (ii) taking 100 mu l and enriched culture medium added with enriched liquid culture medium, oscillating and culturing for 15-20 hours, repeating for 2-10 times, (iii) final enrichment culture liquid with gradient dilution for 103-109 times, (iv) separating B. subtilis on the culture medium by lineation, selecting obtained strain, purification, and preservation; and (2) a production method of the B. subtilis XWJLSP-1 wettable powder, comprising: preparing a fermentation medium from starch sewage, corn steep liquor, magnesium sulfate and calcium carbonate; introducing sterile air into a fermentation medium tank to be subjected to fermentation culture; and adding kieselguhr and carboxymethylcellulose to form a filling material when the quantity of thalli in the culture liquid reaches more than 1x1010/ml, carrying out reduced pressure evaporation to reach 60% water content, and then carrying out spray drying.