Abstract: The effect of plant density on the plant character, yield character and yield, the trait of changing trends of the leaf area per plant and leaf area index（LAI）were studied under the condition of super-high yield in this experiment. The result showed that plant height and the height of bottom pods were heightened along with the increase of density. The thickness of stalk, nods, branch of No., length of branch reduced along with the increase of density. The lodging on soybean was sharpened along with the increase of density. The No. of effectual pods and seeds per plant, seed weight per plant reduced along with the increase of density. The relation of 100 seeds weight and plant density wasn’t prominent. LAI increased along with the increase of density. The comprehensive performance of 45.0 plants per ha was the best, with the yield per ha 5547.81kg.