Abstract: To understand the effect of microbial community structure in pit mud on the quality of base liquor, the quality of base liquor produced in different pits with the same age, raw materials and technology were investigated. The volatile components of two base wines from Henan Yupo distillery with the same pit age, raw materials and process were detected by headspace solid phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS),and the composition and diversity of the microbial community in the pit mud of the corresponding cellar were analyzed using high-throughput sequencing technology. The results showed that the quality of the two base liquors was different. The base liquor with higher ethyl hexanoate content and more esters in the volatile components with relative content > 1% had better quality. The bacterial and fungal communities in pit mud with good base wine quality were more evenly distributed, and the abundance of Caproiciproducens, Clostridium_sensu_stricto_12 related to liquor flavor was higher. Therefore, the microbial community structure of the pit mud is the root cause affecting the quality of liquor.