Establishing the selenium threshold for soils in selenium-rich wheat producing areas in Shaanxi Province is closely related to the lean, fine-scale, and accurate production of natural selenium-rich wheat. Moreover, it can improve the utilization efficiency of selenium-rich land, thus promoting the development of selenium-rich industry in this province. This study determined the selenium threshold of soils in selenium-rich wheat producing areas in Shaanxi at 0.27×10^-6 based on the 1∶250 000 land quality geochemical survey data, the selenium concentration data of 544 sets of soil samples and corresponding wheat seed samples collected in Shaanxi in recent years, the lower limit of geochemical anomalies of selenium in topsoil in the Guanzhong area, and the wheat-soil function. The empirical study showed that the validation set formed via random sampling yielded a selenium accumulation rate of 83.78%, while the third-party inspection yielded a selenium accumulation rate of 87.14%. The wheat produced from selenium-rich land delineated based on the selenium threshold 0.27×10^-6 satisfies the recommended nutrient intake of selenium (60 μg/d) stipulated by the Chinese Nutrition Society. Furthermore, the area of the selenium-rich land is about 1 500 km² (2 250 000 mu), increasing by 640 km² (960 000 mu) compared with that of land delineated based on a selenium threshold of 0.3×10^-6. Therefore, determining selenium-rich soil threshold by crop species can greatly improve the utilization efficiency of selenium-rich land, thus promoting the development of the selenium-rich industry. This study provides a scientific basis for setting selenium enrichment criteria for soils in Shaanxi Province.