Whole plant com fertilized with or without nitrogenous fertilizer during its growth was harvested at milk matured stage for silages. The lactic acid bacteria inoculants Lactobacillus＞6×10¹? cfu/g, Pediococcus＞2×10¹? cfu/g) was used at 0.01 g/㎏ of fresh matter. Cellulase (CF) (concluding cellulase, acremmoocium and trichioderma) was used at 0.033 g/㎏ of fresh matter. And the mixture of lactobacillus and enzyme (LF+CF) were used respectively 0.01 g/㎏ and 0.033 g/㎏ of fresh matter. After 45 days, when the silages had been made, opened to air and sampling for the analysis of nitrate contents and nitrite contents at 0, 1, 3, 6 and 10 days. The results showed that, the nitrate content of fertilized com silages was higher (p＜0.05) than that of unfertilized com silages significantly at the beginning of opening the silages. As the day's extension, the nitrate content of all silages trended to decline. For the fertilized com silages, the nitrate content of untreated silages higher (p＜0.05) than that of treated silages and declined sharply throughout the process. This phenomenon appeared from 3 day point to 10 day point for treated silages. For unfertilized com silages, there was no significant difference between untreated silages and treated silages at 0 day point. The nitrate content of untreated silages sharply declined from 0 day to 10 day point, which of treated silages began at 3 day point. From above, we can conclude that nitrogenous fertilizers can affect the nitrate content of com silages, and adding LAB and enzyme can retard the nitrate transforming into nitrite.