The invention relates to the technical field of biomass energy, in particular to a method for comprehensively utilizing biomass resources. The method mainly includes: using a cutting machine or a stirring machine to smash and evenly mix biomass under room temperature, sufficiently combusting in a gasification furnace, subjecting generated gas to cyclone treatment, filtering and washing, feeding into a calcium hydroxide solution, drying to obtain biomass, pressurizing, combusting in a burner to provide heat for a waste heat boiler and provide heat for steam engine unit power generation or internal combustion engine unit power generation, and activating solid residues generated in insufficient combustion with a modification activating agent to prepare activated carbon particles. The method has the advantages that by purifying and pressurizing the biomass, air pollutants such as H2S in the biomass are reduced, and the combustion efficiency of the biomass is increased; in addition, the biomass is activated by the modification activating agent, so that the activity of the activated carbon particles prepared by the biomass is enhanced.