The invention provides strong abrasive belt base paper and a preparation method. The strong abrasive belt base paper is high in strength and fine in flexibility and impermeability and is not layered. The preparation method for the base paper includes steps that 1, wood pulp is disintegrated, 2, the pulp is proportioned, materials are blended, and a pH (potential of hydrogen) value in blended materials is controlled to range from 6.5 to 7.0, 3, interlayer spraying of the paper on a screen is carried out, 4, a back is prestressed, replaced and dried, and 5, front and back impregnation, glue application and drying are carried out. Multiple times of glue application are realized in a paper making process, glue content in the paper is increased, the strength of a product is improved, and the product is not layered and is fine in flexibility and impermeability. The heavy base paper is high in interlayer peeling strength, dry and wet strengths of the heavy base paper meet indexes of like imported products, oil impermeability of the heavy base paper can completely meet the strong abrasive belt production requirement of the industry of coated abrasive tools, and performances, such as the strength, the flexibility and the like, of a base of a produced abrasive belt product are improved obviously.