Permanent magnet roller eddy current sorter is an important device for extracting metal slag at the fire site, but the existing sorting equipment has problems such as low sorting efficiency and large volume and weight, and it needs to be optimized. The magnetic system space of the core components of the sorter is studied. The magnetic system space structure model of the sorter is established. The working principle of the sorter is explained, and the calculation equation of the magnetic system space of the magnetic block for a certain magnetic roller is given. Then, the law of the magnetic induction intensity distribution of the original magnetic system space is analyzed by using the finite element method, and the magnetic induction intensities of the magnetic roller under different outer diameters, different inner diameters, and different iron ring thicknesses are compared. An optimization design scheme for the original eddy current sorter is proposed, which reduces the weight and improves the efficiency of the sorter.