Entrusted by the user, the NdFeB temperature irreversible loss measuring instrument is designed to meet the foreign users' assessment of material quality and provide data. The heating temperature is normal temperature ~ 200 ℃, and the magnetic field range is 0 ~ 1T. The design method is actually relatively simple, or companies that currently have permanent magnet material BH measuring instruments can use the equipment at hand to complete it, saving costs. That is, the heating pole of the electromagnet is used to complete the heating of the magnetic steel (the heating of the closed-circuit electromagnet and the conduction heating through the fixture), with the flux meter and the standard One-dimensional Helmholtz coil measures the magnetic flux (or magnetic moment) changes at different temperatures to obtain the thermal magnetic flux density loss curve, which is obtained by testing the magnetic flux change back to normal temperature after heating Reversible magnetic flux density loss curve, while obtaining irreversible magnetic flux density loss curve. The electromagnet that can apply the reverse magnetic field can also be used to obtain the diamagnetic curve of the material under high temperature conditions, which can be used to assess the application range of the magnet in the magnetic circuit.