In order to investigate the effects of land use/cover change on soil selenium (Se) content and its forms, topsoil samples (0-20 cm) were collected from dryland (40 samples), paddy fields (10 samples), and forests (natural and secondary forests, 40 samples) in Jiangjin District, Chongqing, an region with a nearly 20-year history of the "Grain for Green" program. Laboratory tests were conducted to analyze soil pH, organic matter, major elements, total Se, and its five forms. The results showed that: 1) Total Se, water-soluble Se, Fe-Mn oxide-bound Se, and organic-bound Se were higher in forest soil than in those of dryland and paddy fields. 2) Total Se, water-soluble Se, and Fe-Mn oxide-bound Se in secondary forest soil were significantly higher than that of in dryland. 3) The soil organic matter content in both natural forest and secondary forest was higher than that in dryland, and soil organic matter was significantly positively correlated with total Se, exchangeable and carbonate-bound Se, Fe-Mn oxide-bound Se, organic-bound Se, and residual Se in the soil. The above results indicated that land cover types and their conversion significantly influence soil selenium content and its speciation. This study provides a scientific basis for better management and development of Se-rich soil resources.