Abstract: Toexploretheabsorptionandenrichmentmechanismofexogenousseleniumin Brassica tumida Tsenet Lee, we carried out field experiments with foliar spraying different concentrations of Na2SeO3 (0, 1, 2.5 mg/L), and studied the rules of selenium absorption, transformation and utilization of Brassica tumida Tsenet Lee, and the effect of selenium on the growth of Brassica tumida Tsenet Lee. The results showed that: at the suitable concentration of Se (1 mg/L), the yield of Brassica tumida Tsenet Lee increased but the difference was not significance; the content of nitrate in Brassica tumida Tsenet Lee reduced to the lowest point by the foliar spraying, while the content of reducing sugar, free amino acid and Vc showed an opposite trend and reached the highest point with the same concentration (1 mg/L), compared with the control, increased by 46.73%, 40.41%, 13.36%, respectively; with the increasing of foliar spraying Se, the concentration of total Se and organic Se increased by 74.0%-271.5% and 46.1% - 193.9%, respectively, compared with the control, and showed a significant positive correlation; with the increasing concentration of Se in Brassica tumida Tsenet Lee, the transformation rate of organic Se significantly increased by 23.57% and 19.33% compared with the control respectively.