The invention relates to the technical field of biological engineering, and particularly relates to a simple fermentation medium for producing vitamin B2 by utilizing bacillus subtilis. The simple fermentation medium is prepared from the following components in percentage by weight: 0.3-1.0 percent of urea, 1-3 percent of yeast extract powder, 0.2-1.0 percent of sodium chloride, 5-20 percent of cane sugar, 0.05-0.5 percent of magnesium sulfate and 0.1-0.5 percent of ammonium sulfate. According to the simple fermentation medium for producing vitamin B2 by utilizing bacillus subtilis, the simplefermentation medium is designed by optimizing a carbon source and a nitrogen source in the fermentation medium, can be used for shortening the fermentation cycle of vitamin B2 and quickly verifying the performance of bacillus subtilis in synthesizing vitamin B2, so that the process for breeding high-yield vitamin B2 strains can be greatly simplified.