The invention discloses a stable casting mould material. The stable casting mould material is prepared from the following raw materials in parts by weight: 50-80 parts of unsaturated polyester resin, 5-10 parts of methyl methacrylate resin, 30-50 parts of iron, 5-10 parts of carbon, 20-40 parts of styrene, 5-10 parts of zinc sulfide, 5-10 parts of barium sulfate, 2-5 parts of methyl ethyl ketone, 4-8 parts of silicon, 6-15 parts of a diluent, 10-20 parts of filler, 1-2 parts of a curing agent and 20-40 parts of glass fibers. The stable casting mould material disclosed by the invention has the advantages that compressive strength of the material can be greatly improved, so that the obtained stamping mould can have longer service life, the obtained mould added with resin is light in weight, in the production process, moulds in various shapes can be made conveniently as required, and the made moulds are difficult to deform after being cured.