Abstract: The ANSYS Workbench simulation software was used to analyze the temperature field distribution of the tube vacuum heat treatment furnace. The optimized design parameters of heat treatment furnace insulation layer, workpiece box and screen were obtained by simulating the influence of the placement position/thickness of the insulation layer, the thickness/material of the workpiece box, and the thickness/material of the screen on the range and average temperature of the interior average temperature zone of the furnace. After optimization, the average temperature zone length can be increased from 240 mm to 320 mm, which was increased 33.33%, and the average temperature was increased from 958.25 ℃ to 962.94℃. Finally, the temperature field of Nd₂Fe₁₄B samples was simulated by the optimized parameters of heat treatment furnace.The results show that the average temperature range and average temperature of Nd₂Fe₁₄B permanent magnet have been improved obviously. The average temperature of the magnet increases from 959.07 ℃ to 963.06 ℃, and the temperature fluctuations of the magnet obviously stabilize, which is optimized from ±1.06 ℃ to ±0.21 ℃.