The invention discloses a filter material for removing formaldehyde and a preparation method thereof and belongs to the technical field of degradation of formaldehyde. The filter material is composedof powder and liquid; the powder is composed of the following components by weight percent: 20%-30% of kaolin, 25-35% of sepiolite, 13%-20% of attapulgite, 20%-25% of kieselguhr, 0.5%-2% of aluminum oxide powder, 0.1%-1% of metal foil powder, 1%-5% of titanium dioxide powder and 0.2%-2% of copper sulfate powder; the liquid is prepared from the following components by weight percent: 16%-25% of dispersion medium, 18%-35% of wear-resisting medium and 45%-65% of water. The preparation method comprises the following steps: mixing the powder and the liquid at mass ratio of 1:0.45, and then successively passing by a pelletizer, a cylinder drier machine and a basin type drier machine under working state, forming grains by the powder and the liquid, and reducing the water content of the grains tobelow 1%, thereby increasing the efficiency of degradation of formaldehyde and achieving the removal rate to 93.1%-97.6%.