Abstract: Corn stalks from Zea mays L, were served as experimental material to study the effects of N-fertilizer (urea 0,150,300,450 kg/ha) on the nutritional value by using chemical analysis, in vitro two-stage digestion, in vitro gas production and sheep feeding trial. The results showed that the corn stalks had a linear (P<0.001) increase in the contents of CP, true protein, amino acids, nonessential amino acids, essential amino acids and Ca as quantity of urea fertilized increased, and total saccharide content did not change with urea under 300 kg/ha and had a negative linear correlation with urea above 300kg/ha. N-fertilizer had little or no effect on EE, ADF content of corn stalks. The in vitro digestibilities of DM, CP, NDF and ADF of corn stalks increased (P<0.01) in a linear (P<0.001) with the application of N-fertilizer, but when urea dose was upon 300 kg/ha, the function was not enhanced. Daily gain, feed conversion and economic return increased after the lambs (Fat-tailed Han-yang) were fed the silage of the corn stalks fertilized with urea. When corn plants were fertilized with urea 300 kg/ha, the result of feeding was the best. In conclusion, the contents of chemical components of corn stalks were alternated, and moreover, nutritional value of corn stalks was increased after corn plants had been applied with N-fertilizer.