Abstract: The effects of Se on the seedling growth of Italian ryegrass under different N sources are studied. The results show that the low concentration of Se has no significant positive effect on the growth of Italian ryegrass seedlings, but can increase the soluble protein content in root and soluble sugar content in shoot significantly. Se conc.≤0.10mg／L treatment can increase the dry matter weight of root and soluble protein content in shoot. Se 1.0mg／L treatmentcan decrease the seedling growth significantly and make it chlorosis. Urea-N increases the dry weight of Italian ryegrass seedling with dark green color. The mixed application of Se, Si and Se and Si has no positive effect on the increase of seedling weight and chlorophyll content in leaves under the same N source.