This invention discloses a Bacillus subtilis strain L-510 CGMCC No.1563 and the application thereof. The lab analysis shows that the changes of the crude oil processed by this strain have the following characteristics: (1)the rang of the light components is broadened, the content of the non-hydrocarbon components is averagely increased by 2.09%, and the content of asphaltene is averagely decreased by 1.29%, (2) the rate of wax is averagely decreased by 17.56%, and the rate of colloid is averagely decreased by 26.54%, (3)the flow capacity of the crude oil is improved, and the initial apparent viscosity number of the viscosity-temperature curve is decreased by 50% campared to the value before the procession. The result of the microbial huff and puff field test using this strain conducted in Pubei Oilfield shows that, in the four months after being processed by this strain, the effective wells are upto 80%, the liquid output is increased by 44.8%, and the daily oil production is increased by 47.4%. This strain can be widely used in reservoir engineering field, especially in the Microbial Enhanced Oil Recovery(MEOR) field.