The content of sugar and water, and the number of green leaf of sweet corn stalks were measured after ears were har-vested. The results showed that days after harvest was significantly correlated with sugar content (r=-0. 989),green leaf number (r=-0. 952)and water content (r=0.962)of stalks. When the sugar content of sweat comstalks reached above 14%in five to seven days after harvest,it should be the suitable stage to make quality silage according to the number of green leaves and water content.