Abstract: The paper aims to explore the plant type change regular of main emi-determinate soybean under different planting density. Soybean for narrow row solid- seeding‘Hefeng51’was used as experimental material and the dynamic change of plant height, stem diameter, stem node number and internode length, lodging rate and yield were determined. The result showed that the plant height increased with planting density increasing. The stem diameter decreased with planting density increasing. The stem node number had on significant change and the internode length increased with planting density increasing. The plant height increased on account of the internode length increasing. The lodging rate increased with planting density increasing. The yield first increased then decreased with planting density increasing. The correlation of all above traits and the planting density reached significant high level, and the highest yield was achieved with the plant density of 40×104 plant/hm2. It shows that the soybean‘Hefeng51’have high density potential.