Abstract: Mining, smelting and other activities result in arsenic accumulation in soils, with adverse impacts on the quality and safety of agricultural products and soil microorganisms. We monitored the changes of available arsenic content with incubation time after the addition of exogenous arsenic to the yellow soil (YS) and soil derived from purple sandy shale (RS). The community changes of bacteria and archaea in soils without spiked arsenic and soils after 1, 30 and 360 days of exogenous arsenic stress were measured by MiSeq high-throughput sequencing, to investigate the community adaptative mechanism of bacteria and archaea in soil under arsenic stress. Results showed that the available arsenic content in soils decreased gradually with time, which significantly affected the composition of soil bacteria and archaea community. The abundance of dominant bacterial group changed significantly, whereas only archaea with lower abundance changed obviously, and little change occurred in dominant archaea group, indicating that archaea community had high arsenic tolerance and stability. Compared with the arsenic stress time, soil arsenic availability had greater impacts on community structures of bacteria and archaea. The results could provide refe-rences for safe utilization and microbial remediation of arsenic-contaminated cropland.