The purpose of this study is to discuss the ways to consistently feed high quality corn silage(CS). This study evaluated the effect of the corn silage, after a certain time has elapsed, on the chemical composition and fermentation characteristics after feedout during the winter feeding period of the CS. Six samples of CS from four dairy farms(E1, E2, E3, and L1 ) were taken in order to feed the milking cows over a winter feeding Period from November of 2002 until February of the following year, 2003(six samples were taken at the fellowing dates in the following order: sample one was taken on the 23rd Nov. 2002, sample two on the 5th of Dec. 2002, 3rd sample on the 23rd of Dec. 2002, 4th sample on the 7th of Jan. 2003, 5th sample on the 22nd of Jan. 2003, and the 6th sampling was carried out on the 6th of Feb. 2003) at the three sampling sites after the opening of the trench silos at intervals of 15 days. In the dry matter contents of CS, there wasn't any specific tendency according to the elapsed time in the range of 21.3~$27.3\%$ at all low dairy farm(E1, E2, E3, and L1). And the average dry matter contents were 24.1, 25.9, 23.6, and $20.4\%$. Considering the Proper amount of the dry matter of CS during the ripen yellow stage, the appropriate moisture content was $33\%$ (NRC, 1989), and these dry matter contents were all low. A consistent tendency was not found in the contents of CS. The average of CP contents were 10.2, 8.0, 8.5, and $9.8\%$ at the E1, E2, E3, and L1 farms, and there were significant differences. The TDN contents of CS were not different among forms according to the time elapsed. The pH, according to the time elapsed after opening of the CS, there were no differences at each of E1, E2, E3, md L1 farms. Average pH were 3.5, 3.9, 3.6, and 4.1, md all of them were in normal range. In the lactic acid contents of CS, a consistent tendency was not found among four farms. But according to the time elapsed. there was a goat difference from 1.13~$7.8\%$ The acetate, propionate, and butyrate contents of CS were very low. In this study, there was no significant difference in the CS's chemical composition and fermentation characteristics according to the elapsed time at all four dairy farms. Considering the proper dry matter contents of CS during the ripen yellow stage, the appropriate dry matter content was $33\%$, and dry matter contents of few farms were all low. To enhance the quality of corn silage should be ensiled com at proper dry matter content range from 28 to $35\%$ Therefore, content of the corn plant should be always be closely monitored prior to beginning harvest.