Abstract: In order to develop a permanent magnet magnetic circuit high intensity magnetic separator， the magnetic field characteristics of the permanent magnet closed magnetic circuit workspace are studied in depth，and the magnetic field strength parameterization model of the permanent magnet closed magnetic circuit is established. The influence of magnetic circuit structure parameters on the magnetic field strength and magnetic flux leakage in the workspace is simulated and analyzed. It is found that the magnetic field strength in the workspace is related to the shape of the permanent magnet，the magnetic pole distance and the working width of the workspace. According to the simulation analysis results，the larger the ratio of the cross-sectional area of the permanent magnet to the height，the smaller the magnetic pole distance，the smaller the working width，and the higher the magnetic field strength in the working space. According to the optimized magnetic circuit model，a test prototype is made，and the correctness of the simulation model is verified by magnetic field measurement.

Key words: permanent closed magnetic circuit, magnetic field strength, leakage coefficient