Abstract: Using single factor experiments and response surface experiments, with the acid yield and cell density as indicators, the optimization of fermentation condition of Lactobacillus casei YQ336 isolated from natural fermentative acid juice was carried out from the aspects of fermentation time, fermentation temperature, initial p H, inoculation amount, carbon source and carbon source addition.The optimum fermentation conditions were as follows: fermentation time 48 h, fermentation temperature 37 ℃, initial p H6.0, inoculation amount 3%, carbon source was glucose, adding 5%, under this condition, lactic acid production was28.81 g/L, total acid yield was 34.245 g/L.The results showed that Lactobacillus casei YQ336 could be fermented into acid slurry bean curd coagulant under this condition and used in industrial production point to make acid slurry bean curd.