The soil seed bank (SSB), as a potential provenance, plays an important role in the natural recovery and succession of vegetation and ecological restoration. In this study, four plant communities were evaluated in a desert steppe area in Yanchi County, Ningxia. We investigated the relationship between soil physical and chemical properties of plant communities fenced for 16 years to reveal the SSB distribution characteristics of the desert grassland community and succession trend and how changes in soil quality affect SSB characteristics. The results showed that (1) the species composition and seed density of SSBs in various plant communities were different, and the seed density of the same species was different in various plant communities. Moreover, the species proportion of four types of plant communities in SSB included Gramineae, Compositae, and Chenopodiaceae (26.19%, 21.43%, and 19.05%, respectively), accounting for 66.7% of the total species. (2) Many perennial and annual plant seeds, and few shrub and semi-shrub seeds were found in the SSBs of the four communities. (3) The species number and seed density in the SSBs of the four plant communities were as follows:Achnatherum splendens community > Sophora alopecuroides community > Artemisia ordosica community > Kalidium foliatum community; the species number and seed density showed a decreasing trend with soil depth. (4) Four indexes (Shannon-Wiener, Simpson, Pielou, and Patrick) indicated the same tendency, that is, A. splendens community > S. alopecuroides community > A. ordosica community > K. foliatum community. In addition, the SSB of A. splendens community had the highest similarity to that of A. ordosica community, but the SSB of A. ordosica community had the lowest similarity to that of K. foliatum community. (5) The soil species diversity index of SSB was positively correlated with soil pH, water content, and available nitrogen and negatively correlated with soil electrical conductivity. Soil pH and electrical conductivity had a significant effect on species diversity in the SSBs. After enclosure, the species number, seed density, and biodiversity of SSB increased, especially, those of the perennials and annuals; the species number and seed density of Gramineae and Leguminosae were both greater than those of Compositae and Chenopodiaceae. All the results indicated that fencing improved not only the grasses but also positive succession.