Increasing plant density is necessary to raise corn yield further in the middle semi-humid region of Jilin province. The key in corn breeding program is to improve the crop adaptibity to the increasing density. Due to the lowel machanizalion and the poor management, it is not easy keeping all the seedlings. The concept of hybrids with the density telorence should have more extensive range, generally from 50 000-60 000 plants/ha. The hybrids must have the following characteristics: (1) a stronger stalk quality; (2) a longer stay green of leaf; (3) shed and silk at the same time; (4) a stronger seedling vigor; (5) more convergent apperearance of plant.