The invention provides a method for preparing biochar fuel from kudzu vines, and relates to the technical field of biochar fuel. The method comprises the following steps: naturally air-drying and crushing the kudzu vines; mixing kudzu vine powder with a salt solution according to a mass ratio of 1:(15-25); immersing and drying to obtain mixed materials; placing the mixed materials in a heating furnace for anaerobic heating to 350-480 DEG C at a heating rate of 10-20 DEG C/min; naturally cooling after reaching the predetermined temperature and keeping the temperature for 1-2 h to obtain kudzu vine charcoal; grinding the kudzu vine charcoal by a ball mill; sieving with a sieve of 80-100 meshes; adding a modified tapioca starch adhesive and auxiliaries with the mass being 1/9-4/9 times of themass of the kudzu vine charcoal, uniformly mixing, pressing and molding to obtain the kudzu vine charcoal fuel. The kudzu vine charcoal fuel prepared with the method provided by the invention has relatively high charring yield, energy yield and compressive strength.