Abstract: As the third generation of rare earth permanent magnet, sintered Nd-Fe-B permanent magnetic material has extremely high magnetic properties. However, due to the low Curie temperature and poor thermal stability, its application in high temperature industry is seriously limited.With the rapid development of new energy vehicles and wind power generation and other fields, the demand for high coercivity Nd-Fe-B permanent magnetic material increases significantly. In order to overcome the thermal demagnetization effect, further expand the application of sintered Nd-Fe-B magnets at high temperature, developing new technologies to improve the coercivity of magnets has become a current research hotspots. The research progress of grain refining, grain boundary doping and grain boundary diffusion technology was reviewed, and the development trend of high coercivity sintered Nd-Fe-B permanent magnetic material was prospected.