Abstract: To enhance the flavor profile of yeast-fermented steamed bread, this study employed a liquid fermentation method to process traditional sourdough. The liquid fermentation parameters were optimized using single-factor experiments and response surface methodology. Subsequently, the fermented sourdough was dried into powder form using freeze-drying and spray -drying techniques. The impact of the resulting sourdough powder on the quality and flavor characteristics of steamed bread was systematically investigated. Single-factor experiments were conducted to evaluate the effects of sourdough percentage, dough-to-water ratio, fermentation duration, and fermentation temperature on the quality attributes of steamed bread prepared with sourdough powder. Additionally, response surface optimization was performed using a Box-Behnken experimental design. By considering the taste score of sourdough powder steamed bread as the response variable, the optimal fermentation conditions were determined: a sourdough percentage of 40%, a dough-to-water ratio of 5∶11, a fermentation time of 30 h, and a fermentation temperature of 32°C. Under these optimized conditions, the sensory evaluation score of the sourdough powder steamed bread was 48.72, which closely aligned with the predicted response value of 48.65, demonstrating no statistically significant difference. Compared to the control group, the incorporation of sourdough powder significantly enhanced the flavor profile of the steamed bread. The addition of sourdough powder could significantly increase the volatile flavor substances such as acids, ketones, aldehydes and esters in steamed bread, and the sourdough powder prepared by spray drying exhibited a more significant effect on improving the flavor characteristics of the final product.