The invention discloses a heavy metal ion absorbent and a preparation method thereof. The heavy metal ion absorbent is mainly prepared from 70-95 parts of water-based black ink printing effluent extract and 5-30 parts of pumice stone and sepiolite in parts by mass. The preparation method comprises steps as follows: the water-based black ink printing effluent extract is blended into paste with a certain solid content, and appropriate alkaline substances are added until the paste is neutral; a certain quantity of pumice stone and sepiolite granules are added to sludge and stirred to be uniform, so that the specific gravity of the sludge is adjusted; the sludge is heated to 50-90 DEG C while being stirred and then hydrated until the sludge becomes blocky, the blocky sludge is subjected to hot pressing until the water content is lower than 50% and then dried, and water obtained during dehydration is drained; the sludge is heated to 350-750 DEG C in a vacuum state and kept at the temperature for 1-5 h; the sludge is broken into granules after being cooled to be at a certain temperature, sprayed with a wetting agent solution in the mass concentration being 0.05%-0.2% and mixed uniformly. The prepared heavy metal ion absorbent can be recycled after regeneration.