Abstract: This study determined to investigate a strain of Lactobacillus plantarum-Gm4 (LP-GM4) isolated from the traditional sourdough. A response surface experiment was designed according to Box-Behnken central combination principle to optimize the fermentation conditions of LP-Gm4 based on the single factor experiment, and low temperature drying technology was used to prepare sourdough powder. The results showed that the optimal fermentation parameters of LP-GM4 were as follows: fermentation temperature of 31.8 ℃, fermentation time of 13.5 h and LP-Gm4 adding amount of 10 lg(CFU/g) wheat flour. The pH, TTA value and LP-GM4 bacteria count of the sourdough powder were 3.51, 17.8 and 7.2×10⁸ CFU/g, respectively. The sourdough inoculated with LP-Gm4 and active dry yeast were used to prepare the steamed bread, using the single time fermentation progress. The skin structure, internal elasticity, taste and smell of the steamed bread were determined to be superior compared to the yeast steamed bread.