Root exudates play a pivotal role in regulating rhizosphere microbial communities; however, the effects of different types of salt stress on rhizosphere rare bacteria via root exudates remain unclear. This study employed targeted metabolomics and high-throughput sequencing to investigate the impacts of three types of salt stress-alkaline, neutral and mixed-on the root exudates and rhizosphere rare bacteria of Leymus chinensis in a pot experiment. Alkaline and mixed salt stress significantly increased the carbon content and C:N ratio of root exudates, while all types of salt stress enhanced the exudate secretion rate. The composition of root exudates significantly influenced the composition of rare bacterial communities in the rhizosphere; however, their quantitative impact was smaller than that of soil pH. L. chinensis mitigated the effects of alkaline and mixed salt stress on the diversity and evenness of rare microbial communities by increasing the C:N ratio of root exudates, though this adjustment may also inhibit the stability of rare microbial networks. Salt stress-induced changes in electrical conductivity altered the differential secretion of root exudates, promoting the diversity and evenness of microbial communities. These findings advance our understanding of how plant root exudates and rhizosphere rare bacteria respond to different types of salt stress, emphasizing the crucial role of plants in modulating rhizosphere rare microbial communities through exudate secretion.