Abstract: In order to determine the effects of biochar application amount on the growth and yield of soybean, a field plot experiment was conducted with soybean Heihe 43 as the material, and four levels of biochar 27 kg·ha^-1（B1）,54 kg·ha^-1（B2）,81 kg·ha^-1（B3）and 108 kg·ha^-1（B4） mixed with conventional fertilization were set up and the ground and underground growth, dry matter accumulation and yield indicators of soybean were analyzed. The results showed that the application of biochar could affect the plant height, stem diameter, root length, root volume, fresh weight and dry matter accumulation of soybean in each growth period, and the increase rates were respectively-27.58%-13.13%, 6.52%-29.62%,-9.65%-0.78%, 17.78%-68.41%,-26.84%-59.79%（fresh weight above ground）, 1.43%-62.88%（fresh weight below ground）, 9.09%-51.49%（dry weight above ground）, and-14.07%-62.26%（dry weight below ground）. The plant height of biocher treatrments increased significantly at the seed filling stage and mature stage, stem diameter of all biochar treatments increased, aboveground fresh weight, dry weight, underground fresh weight, dry weight and root length of B3 treatment had the largest increment. Biochar can increased the yield per plant by increasing pods number per plant, effective pods number per plant, seeds weight per plant and 100-seed weight, and then increased the total yield by 1.57%-7.74%. In general, the promotion effect of conventional fertilization combined with 81 kg·ha^-1 biochar（B3 treatment） on soybean growth and yield was the best.