To explore the effects of biochar application rates on the growth and development of sweet potato. The study used pot experiment（0, 0.75%, 1.1%, 1.5%） and field experiment（0, 20, 30, 40 t/ha） to study the growth,physiological indicators and yield of sweet potato. The results showed that biochar can increase the stem thickness,stem length and leaf area of sweet potato, improve the photosynthetic characteristics of sweet potato leaves, increase the chlorophyll content, SOD and POD activity of sweet potato, and increase root vigor. Treatment IV had significant differences in the number of large and medium potatoes and the yield of the plot from the control, but the differences in the weight of large and medium potatoes and the average yield per plant were not significant. The biochar application rate of 40 t/ha sweet potato has the best growth, the best physiological indicators and the highest yield.