The invention belongs to the technical field of silica gel preparation, and more specifically relates to a preparation method of a silica gel large in pore volume and specific surface area. In the prior art, common silica gel products comprise macroporous silica gel and fine pored silica gel, and it is difficult to achieve large specific surface area and large pore volume at the same time. It is shown in correlational studies that drying method influences silica gel performance. Deep study on the relationship of drying method and silica gel performance is carried out, and vacuum drying and freeze drying are provided. It is shown in study that vacuum drying possesses an advantage of controllable production, silica gel crushing degree can be adjusted by workers based on application purposesso as to obtain silica gel products with target performance; and the steps of freeze drying are convenient. The more controllable production method is provided for production enterprises, the technology is simple and convenient, and the popularization value is high.