Abstract: Sourdough is rich in microbial flora, and the fermentation process will produce complex and diverse flavor substances as well as nutritional factors, which endows the sourdough with unique and strong flavor and nutritional efficacy. In this paper, the structure of the main microflora (lactic acid bacteria and yeast), the correspondence between the dominant microflora species and the flavor substances, and the effect of the fermentation of sourdough on the flavor substances and nutritional properties of steamed bread are reviewed. At present, there is still a lack of sufficient knowledge about the connection between the structure of microflora, flavor substances and metabolites in sourdough and the composition of flavor substances and nutritional characteristics in steamed bread. To further explore the potential value of sourdough, further in-depth studies on the nutritional aspects of key flavor substances as well as their metabolites are needed. This will provide a strong support for revealing the formation mechanism of key flavor substances in sourdough steamed bread, and clarifying the nutritional role of microbial metabolites.