Planting rice is one of the effective ways to improve saline soils, but the underlying mechanisms are unknown. We studied basic soil properties (including pH, salt content, total nitrogen, etc.) and microbial diversity of the bare soil (salt content >4 g/kg, CK), the Suaeda (Suaeda glauca (Bunge) Bunge) soil (JP), and the soil in which rice (cv. Huaidao 5) grew for one (1Y) and three (3Y) years. The results showed that the soil salinity decreased in the order: CK > JP > 1Y > 3Y. The contents of soil organic matter, total nitrogen, dissolved organic carbon, readily oxidizable carbon, microbial biomass carbon, and particulate organic carbon were higher in 1Y and 3Y compared with CK. The Chao 1 index of soil microbiome diversity was about 1.20 times and 1.49 times higher in the soils after rice compared with JP and CK, respectively. Among the soil microorganisms, the top four abundant phyla were Proteobacteria, Chloroflexi, Bacteriodetes, and Firmicutes. In summary, planting rice decreased soil salinity, and increased the content of nutrients and diversity of microorganisms, thereby improving the saline soil.