The invention discloses a method for reducing the fiber breaking rate in the pulping process using waste paper for papermaking. The method includes the steps that large-diameter brooming millstones with blunt teeth on pulping surfaces are selected to serve as the upper millstone and the lower millstone, the angle of a to-be-pulped material flowing past a pulping area is smaller than 360 degrees inthe pulping process, and liquid molecules in the to-be-pulped material in the puling area are subjected to bubble nucleation under the ultrasonic action in the pulping process. In the pulping process, fiber can be quickly broomed, objects adhering to the surface of the fiber are quickly separated, and abrasion and breaking of the fiber are reduced, so that long fiber larger in amount and higher in proportion exist in pulp, damage is less, the quality of the papermaking pulp is better, the utilization rate of the papermaking pulp in the net papermaking technology is increased, the leakage rateand the return rate of the net papermaking process can be reduced, the production cost can be reduced, and corrugated core paper and kraft paper with better quality can be obtained.