Abstract: Using used lithium battery cathode powder as raw material, under the condition of a magnetic field, the cobalt in the cathode powder is leached by sulfuric acid-hydrogen peroxide system. The influence of magnetic induction intensity, magnetization leaching time and leaching temperature on the cobalt leaching rate are discussed. The results show that, in a magnetic field of 230 mT, the leaching time is 100 min, the reaction temperature is 70 ℃, and the solid-to-liquid ratio is 1:100 (the sulfuric acid concentration is 3 mol/L), and 3 mL/g H₂O₂ is added for the test. The leaching rate of cobalt reaches 99.61%. Compared with the same condition without magnetization, the leaching rate of cobalt is increased by 6.02 percentage point. At the same time, when the amount of sulfuric acid is reduced by 20%, magnetic field enhanced leaching can increase the leaching rate of cobalt by 4.62 percentage point. The mechanism of magnetic field-enhanced leaching is to accelerate the diffusion rate of hydrogen ions and promote the reduction of Co³⁺ by hydrogen peroxide, thereby increasing the leaching rate of cobalt in the leaching reaction.