Abstract: High scattered red amorphous nano selenium was synthesized in the presence of food-grade sodium alginate, employing SeO2 and NH2OH·HCl as the reactants.Then Nano selenium/chitosan composite particles were synthesized by compounding Nano selenium with chitosan and corn starch.The selenium sustained-release behavior of complex had been studied in simulation digestive juice, some factors influencing the release rate of selenium were systematically investigated, such as the pOH of simulation digestive juice, the sustained-release temperature and time.Experiments showed that Nano selenium complex was fit for slow-release.The optimal sustained-release conditions as follows:the pOH of simulation digestive juice was 12.8, sustained-release temperature was 38℃, sustained-release time was 2.8h.Under the condition, the release rate of selenium was up to 68.43%.The analysis capability of model was significant as the relative error between experimental result and model predicted value was 0.48%.