Abstract: Selenium plays an important role in anti-oxidation and disease prevention. In recent years, more and more studies have been conducted on the relationship between Selenium and human health, especially the correlation between the physiological functions of Selenium and diseases. Therefore, the characterization of Selenium levels in the human body requires appropriate Selenium detection technology to accurately determine the Selenium content in the human body, which is of great significance for guiding accurate selenium supplementation. Since the Selenium needed by the human body cannot be synthesized by itself and needs to be taken in from the outside, dietary Selenium supplementation is more suitable as a daily Selenium supplementation method than Selenium nutritional supplements. As the main source of dietary Selenium, its development is of great significance to dietary Selenium. This review describes the absorption and metabolism pathways of organic and inorganic Selenium in the human body in detail, and introduces their absorption methods and transport pathways. At the same time, the Selenium biomarkers used to accurately characterize the human Selenium level are described, including traditional Selenium biomarkers and emerging markers. In addition, the traditional Selenium detection technology is analyzed in combination with markers. Regarding the shortcomings in the traditional technology, the new Selenium detection technology is described with the optimization of pre-detection pre-treatment, technical combination and technological innovation as the main content. The development of Selenium-enriched food has important value for dietary Selenium supplementation. Natural and artificial Selenium-enriched foods are described, and the application of biotransformation methods and nanotechnology in the development of artificial Selenium-enriched foods is highlighted.