Nano-selenium (selenium nanoparticles,SeNPs) has been widely used in agriculture,medicine,biology and other fields due to its characteristics of easy absorption,low toxicity,and high biological activity,etc..However,SeNPs are unstable,easy to aggregate,and difficult to recycle.To overcome these shortcomings,researchers have been devoted to exploring the new methods of preparation and regulation of nano-selenium materials.This article mainly summarizes the methods of regulating the activity of nano-selenium materials and introduces their applications in the fields of biosensing,imaging,anti-bacteria,anti-virus,cancer therapy,and anti-oxidation.Furthermore,the current challenges and future perspectives are proposed.It will provide references for understanding the properties of nano-selenium and developing functionalized nano-selenium food.