Abstract: A strain of Lactococcus lactis subsp.lactis with accelerating the separation of starch and good fermentation properties was isolated from Beijing Douzhi by natural fermentation. This strain was named Lactococcus lactis subsp.lactis LLY003 and applied to fermentation beverage and the supernatant of mung bean starch as substrate. Then the single factor experiment and orthogonal experiment were designed for optimizing the technology parameters. The optimal fermentation condition was inoculated amount 8% at 39 ℃ for 6 hours with 6% aucrose, under these conditions, the values of sensory reached 94 scores and the viable cells reached 3.22 × 1011CFU/m L.The storage shelf life could reach up to 20 days at 4 ℃ and the viable cells above one hundred billion.