The invention discloses a composite biological activated carbon and a rapid preparation method thereof, raw materials thereof comprise coconut shell, bamboo, rice hull, sawdust, wheat straw or rice straw, or the raw materials thereof comprise the rice hull, the sawdust, the wheat straw or the rice straw, corn stalk or corn core, the raw materials are smashed to prepare columnar granules, the direct heating method of the spontaneous combustion type granules is adopted for preparing the carbon, a fixed layer is paved at the bottom of a furnace by taking the granules as the raw materials, the fixed layer is ignited by using ignition materials, the feeding is adopted at the upper part of the furnace and the air induction is carried out at the lower part of the furnace for accelerating carbonization of the granules, the air induction is stopped after the carbonization of the granules, the temperature in the furnace is kept at 430-700 DEG C, the spray cooling method is adopted for activatingand cooling the granular carbon, and a finished product is prepared after 20-30 minutes. A plurality of raw materials are mixed, and more pores are naturally formed, thereby expanding the specific surface area of the carbon, greatly increasing effective micropores, leading the absorption performance to be greatly better than the existing activated carbon of single material and reflecting the unique advantages of the composite material.