Abstract: To study the in-situ remediation method of groundwater microorganisms in a decommissioned mining area with in-situ acid leaching for uranium operation,the groundwater was collected,and the indigenous microbial information was obtained by using the high-throughput sequencing method after fully mixing,to determine the structure and function of the microbial community in the groundwater.The results showed that there were both bacteria and fungi in groundwater,and the diversity of the bacterial community was significantly higher than that of the fungal community.Proteobacteria dominated the bacteria,accounting for 67.23 %,while Ascomycota dominated the fungi,accounting for 89.26 %.FAPROTAX analysis showed that the microorganisms in the groundwater of the decommissioned mining area were mainly methylotrophy,methanotrophy,sulfate respiration and methanol nutrient.