Abstract: The study researches the effect of soybean density of different varieties on the plant height,LAI,the shoot dry weight, the pod numbei,the pod dry weight,the branch number,the stem diameter, biological parameter of soybean.The result shows that, The soybean varieties Mengdoul2,Mengdoul4 can get highter yield on 375 000 plant/ha,the main agronomic traits and the yield traits are better than the other two densities.Under the different density,the oil and protein content are no significant differences.