Abstract: A field experiment was arranged in the Yellow River beach from 2006 to 2008 to study the regulation of selenium (Se) and Se-cobalt (Co) by basal application of combined fertilizers (Na₂SeO₃·5H₂O-570-765 g/hm² and CoSO₄·7H₂O-762-1 548 g/hm²) on the nutrition of alfalfa and animal products through the “soil-pasture-feed-animal chain” (SPAFC). Alfalfa had a strong capacity to absorb Se from soil fertilizers and to convert inorganic Se to organic Se. Se and Co combined application increased the abilities to absorb and convert inorganic Se, thus effectiveness and security of Se could be greatly enhanced. When application rates of Se and Co were 765 and 762 g/hm² respectively, Se-Co combined fertilizer enhanced the contents of crude protein (CP) and ether extract (EE), but had no apparent effect on the crude fiber (CF) content or non-nitrogen extract (NFE), suggesting that feed value was greatly increased. Other Se and Se-Co combined fertilizers increased CF contents, reduced EE contents but had no significant effects on other nutrients. Se and Se-Co combined fertilizers significantly (P<0.05) enhanced the contents of Cu, Fe, Mn, and Zn. Se-Co combined fertilizers were better than Se alone fertilizers. When alfalfa meal (rich in Se and Co) was 5% of diet, Se contents of animal products were significantly enhanced. There were other significant correlations (P<0.01) between Se contents in animal products, in pasture, and in soil.