Six hybrids that utilized widely on maize production in China were chose as the materials in the study. Changing trend of hybrids agronomic characteristics and yield with planting density were made by split plot design. The results indicated that rows per ear, kernels per row, ear length, ear diameter, kernel length, 100-kernel weight and stem diameter reduced gradually; barren tip, plant height and ear height increased gradually; shelling percentage and yield increased first and then decreased; while volume weight showed decreasing first and then increasing. It could draw the conclusion that a reasonable increase in planting density could promote the yield of maize production with choosing suitable varieties.