The invention relates to a method for producing water-absorbing polymer particles, comprising the steps of polymerizing a monomer solution or suspension, drying the obtained polymer gel, and grinding and classifying the dried polymer gel, wherein the grinding is carried out by means of a multi-stage roller mill, the first grinding gap has a width of 500 to 5,000 µm, the product mass flow passing through the first grinding gap is guided to the second grinding gap by means of a magnetic separator, and the second grinding gap has a smaller gap width than the first grinding gap.