The invention relates to a casting method for preventing a large-scale steel casting surface from generating orange peel defects. The casting method includes the steps of modeling, coating spraying and mould assembling pouring. The step of coating spraying includes spraying of a first coating layer and spraying of a second coating layer, coating adopted in the first coating layer is emery powder coating, coating adopted in the second coating layer is zircon powder coating, the method for spraying the first coating layer is that the emery powder coating is sprayed to the surface of a steel casting cavity through a spraying machine, the spraying thickness is 0.2 mm to 0.3 mm, the method for spraying the second coating layer is that the zircon powder coating is sprayed to the first coating layer through the spraying machine, and the spraying thickness if 0.2 mm to 0.3 mm. The zircon powder coating layer and sand mould chromite sand are isolated through the emery powder coating layer, the zircon powder coating layer is not in direct contact with the chromite sand, and therefore the aim that the emery powder coating and molten steel are not in direct contact is achieved, and the problem of reactive sintering of the zircon powder coating and the chromite sand is avoided.