The invention discloses a method for preparing gas, liquid and carbon products by biomass pyrolysis. The method comprises the steps that firstly biomass raw materials such as residues of branches andleaves after extracting essential oil from wood chips, bamboo chips, chestnut shells, oil tea shells and natural spices are mixed with water, the moisture content of the raw materials is controlled tobe 25-80%, and then the raw materials are charged into a cracking furnace; inert gas is introduced before cracking to pump out air in the system; temperature programming and cracking are performed, and the temperature is maintained at 150 DEG C, 200 DEG C, 300 DEG C and 400 DEG C in the temperature rising period, and the final temperature is 500 DEG C; liquid obtained by cracking is mainly an aqueous solution of acetic acid, furan and phenol derivative organic compounds, uncondensed combustible gas is mainly H2, CO, methane, ethane, propane, and solid is biomass charcoal; and acid, such as phosphoric acid, sulfuric acid and hydrochloric acid, of 0.1-20% of the mass of the biomass raw materials is added, and the selectivity of furfural can be increased.