The morbidity and mortality peak of the farmed Procambarus clarkii isoccurs around May every year, which and is called the "Black May" disease.And more and more Increasing evidence shows that intestinal homeostasis and its the flora composition are closely related to host health.In order to To reveal the changes in the intestinal flora of Procambarus clarkii after the onset of "May plague", the high-throughput sequencing technology of 16SrDNAthe 16S rDNA gene was used to analyseanalyze the composition composition and diversity of the bacterial community in the intestines of Procambarus clarkii with in healthhealthy and "May plague". samples. The results showed that there was no significant difference in intestinal abundance and or diversity between the disease group and the control group, but the composition of the dominant flora changed.