Abstract: Objective: To investigate the protective effect of trehalose on Lactobacillus in yogurt. Method: Measuring the nutrition index dynamic changes of yogurt with 4% trehalose,such as sensory index,acidity,protein content and Lactobacillus quantity.Results: Storing for 12 days in 20 ℃,the protein content of 4% trehalose group showed no significant difference compared with control group. The sensory index and acidity were declined slightly,while the quantity of Lactobacillus were significantly higher than that of control group. Conclusion: Under the liquid condition,trehalose could weaken the damage from low temperature and protect Lactobacillus effectively.