The surface properties and total antioxidant capacity( TEAC) of Casein non-phosphopeptides Na 2 SeO 3 were discussed. Casein was hydrolyzed by Alkaline Protease( Alcalase) and then separated into Casein non-phosphopeptides and Casein phosphopeptides and reacted with Na 2 SeO 3. Hydride Generation Atomic Fluorescence Spectrometry( HG-AFS) was utilized to test Casein non-phosphopeptides,Casein phosphopeptides and Na 2 SeO 3. The result showed that Casein non-phosphopeptides Na 2 SeO 3 was selenium-rich red substance. After analyzed by High Resolution Transmission Electron Microscope( TEM),the most red substances were identified as nanoscale particles. At the same time,the changes of Trolox-Equivalent Antioxidant Capacity( TEAC) in different reactions were measured by ABTS method. Results showed that antioxidant capacity were all enhanced after Na 2 SeO 3 reaction. Among them,TEAC of Casein non-phosphopeptides Na 2 SeO 3 was improved most significantly.