<p>Establishing a temperature field within the sintering furnace aims to compensate for the constraints of traditional experimental approaches in obtaining temperature field data inside high-temperature sintering furnaces. The transient temperature field during the vacuum heating sintering process of NdFeB was numerically simulated. By comparing with the measurement data, the maximum error is within 7%. On this basis, the temperature uniformity of NdFeB workpieces during the sintering process and at the end of sintering was further discussed. The research results indicate that the maximum temperature difference inside the furnace during the sintering process can reach several tens of degrees Celsius, and extending the insulation time can effectively improve the temperature difference during the process. The temperature difference between the surface and interior of the workpiece located in the outer layer is higher than that in the middle layer, and due to the presence of the graphite box, the overall temperature gradient is non-uniform, with the center direction inside the graphite box. By changing the structure and heating process, the uneven temperature distribution during the sintering process was optimized, providing a reference for improving the uneven temperature distribution inside the vacuum sintering furnace.</p>