Planting density affects the traits and yield of maize cultivar Zhengde 306. The best density in Hexi area is 82500 plants/hm2, yielding 16308.15kg/hm2. The ideal range is 75000-82500 plants/hm2, with no significant yield difference. Higher density correlates with shorter ears, fewer rows and grains per ear, but not with ear diameter or weight.