The invention discloses a method for simply preparing MCM-41 with a high specific surface area. The method comprises the following steps: completely dissolving a template agent and organic alkali in deionized water at 30-40 DEG C; slowly dropwise adding a silicon source, continuously keeping the temperature, performing a stirring reaction for 1-3 hours after dropwise addition is finished, and enabling the materials to stand for 60-80 hours at room temperature; filtering the materials to separate out a solid, washing the solid with deionized water, drying the solid, and carrying out heat treatment at 500-600 DEG C for 7-9 hours to obtain the MCM-41 with high specific surface area. The MCM-41 material, or Al-MCM-41 material, is prepared through a hydrothermal synthesis method. When the material is subjected to standing at room temperature, the aging and crystallization processes of the material are carried out at the same time, and the material is not independently subjected to high-temperature crystallization treatment. The method is simple in preparation process, short in time consumption and low in energy consumption. The prepared MCM-41 and Al-MCM-41 mesoporous material has a large specific surface area of more than 1000 m<2>/g and a pore diameter of about 3 nm.