Abstract: Based on the summary of the genetic types and elemental characteristics of national selenium (Se)-rich land, this study explored the arid saline lacustrine sedimentary type Se-rich land. According to the requirements for the delimitation and identification of natural Se-rich land, this study assessed and delimited the Se content, environmental quality, and fertility of soils in Hongshuiquan Township, Ping'an District, Haidong City, Qinghai Province. The results indicate that the soils in the Hongshuiquan area are alkaline, exhibiting a high background level of available Se. Specifically, the content of soil Se ranged from 0.037 mg/kg to 6.544 mg/kg, with an average of 0.352 mg/kg. The contents of Cd, Hg, Pb, and Cr in the soils did not exceed their contamination risk screening values for agricultural land. Additionally, soil As shows potential risk in local plots. In terms of fertility status, the soils exhibit abundant available phosphorus and potassium, and moderate nitrogen and organic matter. Based on the above results and the designated values for Se-rich land in the alkaline soil area, while excluding soil contamination risk zones and considering the continuity, scale, and development and utilization of plots, this study delimited 43 591 mu (1 mu=0.066 7 hectares) of natural green Se-rich land in the Hongshuiquan area, including 13 513 mu for direct agricultural use, and 30 078 mu for potentially utilizable forest land and grassland. Considering local conditions, this study suggests the development of the integrated agriculture and animal husbandry industry in the Hongshuiquan area, centering on the delimited zones and extending to the peripheries with moderate Se content. Planting grain crops and green forage grass in the delimited zones, surrounded by free-range grazing, forming an industrial layout of land with high Se content for grain crops and land with moderate Se content for grazing. Overall, this study holds critical reference significance for further exploring Se-rich land resources in Qinghai Province, scientifically planning the selenium industry, highlighting location advantages, and efficiently transforming resource value.