NOVELTY - Controlling biomass tar produced during the preparation of activated carbon comprises (i) carrying out activation of brown rotten biomass material, and crushing, adding sodium hydroxide, and stirring; (ii) foaming, breaking the foam, centrifuging, filtering, and re-flowing to a buffer tank; (iii) performing molecular distillation, collecting light weight component, and heavy weight components; and (iv) adding a dispersant compound to residue, filtering, washing precipitate with deionized water, and placing the precipitate in a steel-stainless carbonization furnace, and carbonizing.    USE - The method is useful for controlling biomass tar produced during the preparation of activated carbon (claimed).    DETAILED DESCRIPTION - Controlling biomass tar produced during the preparation of activated carbon comprises (i) carrying out activation of brown rotten biomass material by using a high-speed cyclone mill, and crushing into a powder form, placing in an open reaction tank in a volume of 10-15 l, starting to pump, adding 0.5 mol/l sodium hydroxide at a flow rate of 0.5-0.8 m/second into the reaction tank, allowing to stand for 10-15 minutes, and stirring in a high speed rotating machine at a rotating speed of 2500-3000 rotations/minute for 40-60 minutes; (ii) foaming by placing the solution into a foam breaking device having an internal pressure of 2-2.5 mm of mercury, breaking the foam, centrifuging the solution, filtering, and re-flowing the foam-free liquid into a buffer tank; (iii) performing molecular distillation by adding the foam-free liquid into a scraper film evaporator at a rate of 2-4 ml/minute, collecting the flowing out light weight component, and then collecting the heavy weight components from the liquid phase; and (iv) adding a dispersant compound into the residue, to obtain a brown precipitate, filtering, washing the precipitate with deionized water until the pH is 6.5-7, and then placing the precipitate in a steel-stainless carbonization furnace, and carbonizing at 350-500 degrees C for 90-120 minutes.