The invention discloses a plastic material for a water pump housing. The plastic material is prepared from the following raw materials in parts by weight: 120-150 parts of polycarbonate, 20-25 parts of glass fiber, 3-8 parts of nano graphite powder, 10-16 parts of tributyl citrate, 5-10 parts of dioctyl ester, 12-16 parts of epoxy resin, 3-7 parts of a flexibilizer, 2-6 parts of an impact modifier and 5-9 parts of a lubricant, wherein the flexibilizer is a mixture of methyl methacrylate, chlorinated polyethylene resin and ethylene propylene rubber. According to the plastic material disclosed by the invention, by adding the flexibilizer, the impact modifier and the lubricant, the impact resistance of polycarbonate plastic is greatly improved and the using demand of the water pump housing is fully satisfied; and in addition, by adding the glass fiber, the nano graphite powder, the tributyl citrate, the dioctyl ester and the epoxy resin, the tensile property of the polycarbonate plastic is improved, and through the synergistic effect, the service life of the polycarbonate plastic is prolonged.