Abstract: The present invention provides a method for improving tobacco-planting soil by using biochar, and belongs to the technical field of soil improvement. The method includes the following steps: (1) carbonizing agricultural and forestry waste to obtain biochar; (2) pulverizing the biochar to obtain a biochar particle; and (3) mixing the biochar particle with a plow layer of the tobacco-planting soil to obtain biochar-improved soil. Compared with tobacco-planting soil that is not added with the biochar (control), the method provided by the present invention greatly increases carbon and nitrogen contents of the tobacco-planting soil, and significantly increases moisture and available potassium contents of the tobacco-planting soil, which is beneficial to ensure the sorption of soil moisture and nutrients by the tobacco plant.