The invention discloses a method for large-scale preparation of mesoporous silica. The method comprises the steps of 1, mixing of coal ash and auxiliaries containing calcium and sodium, 2, grinding, 3, high-temperature treatment, 4, controllable corrosion and 5, drying so that the mesoporous silica can be obtained. The method effectively achieves the purpose of disposal of coal ash of a thermal power generation plant, and a novel scheme is provided for comprehensive utilization and high value-added utilization of coal ash; the adopted raw materials are low in price, and the synthesis cost is low; the synthesis process is simple and easy to implement industrially, and the great industrial potential is achieved; the synthetized mesoporous silica has the large specific surface area and the pore volume, the pore size distribution is relatively concentrated, and the wide application prospect is achieved in the chemical engineering fields such as adsorption and catalysis.