Selenium (Se) is an essential trace element for human beings and animals (Xia 2013). Diet is the main way for selenium supplementation. Thus, more attention has been given to Se-biofortified agriculture. Selenate (SeVI) and selenite (SeIV) are the main effective forms of Se-enriched nutrient fortifier for soil, which can result in rapid release, easy loss, and incomplete utilization for plants in soil (Liu et al. 2010). Thus, it is of great practical significance to develop a slow-release Se-enriched fertilizer.