The invention discloses a piece of ferromagnetic composite filter paper for an oil filter. The composite filter paper is characterized by being prepared by raw materials in parts by weight as follows: 55-58 parts of mulberry pulp, 40-45 parts of manila hemp pulp, 2-3 parts of nano-silica, 1-2 parts of magnet powder, 3-4 parts of mullite, 2-3 parts of albite, 0.5-1 part of a titanate coupling agent TC-101, 0.7-0.9 part of poly dimethyl diallyl ammonium chloride, 4-5 parts of alkyl ketene dimmer, 1-2 parts of wheat starch, 2-4 parts of animal glue, 3-5 parts of water-soluble phenol-formaldehyde resin, 0.4-0.6 part of nonyl phenol polyoxyethylene ether and 1-2 parts of an auxiliary. According to the composite filter paper, raw ceramic material powder is crushed, so that the powder can be well mixed with paper pulp, and the firmness of the powder in the paper can be increased; the magnet powder is added, so that metal impurities produced during combustion of an engine can be well filtered out, the auxiliary is added, and the filter paper is safe, environment-friendly, good in water resistance and oil resistance, excellent in combination property and long in service life.