In this article, the microbial community structure in pit mud of different quality was analyzed by high-throughput sequencing and pit mud’s enzyme activity was also detected. and then to analyze the correlations among them. The results showed that：The activity of protease, acid phosphatase, catalase increased with quality improvement of the pit mud; But the activity of urease decreased with the quality improvement of pit mud, Dehydrogenase showed the highest activity in the superior pit mud, no significant difference between the secondary and tertiary pit mud. A total of 2050 OTU were obtained in three grades of pit mud,The number of OTU in primary pit mud accounts for 50.6% of the total OUT,More than the sum of the secondary and tertiary OTU number in pit mud;Microbodies of all pit mud are mainly distributed in 9 phylums and 39 genuses. Firmicutes play a leading role in the pit mud , The proportion of Sporobacter, Coriobacterineae,etc in pit mud has a positive correlation with the quality of pit mud.Correlation analysis between enzyme activity and microbial community showed that protease, acid phospha- tase, catalase and dehydrogenase represented significant with microbial community in pit mud. The enzyme activity and microbial community structure in pit mud of different quality all showed certain regularity, and the enzyme activity of pit mud can be used as an indicator to reflect the quality of pit mud to make further analysis.