Manufacturing method of R-T-B sintered magnet

The invention provides a manufacturing method of an R-T-B sintered magnet. By adopting the method, a heavy rare earth element RH diffuses inwards from the surface of R-T-B sintered magnet raw materials without lowering the residula magnetic flux density, and the fracturing and damages of the R-T-B sintered magnet are inhibited. The manufacturing method comprises an R-T-B sintered magnet raw material preparing step, an RH diffusion source preparing step, a step for loading the R-T-B sintered magnet raw materials, RH diffusion sources and stirring auxiliary parts in a processing chamber; and an RH diffusion step for moving the R-T-B sintered magnet raw materials, the RH diffusion sources and stirring auxiliary parts and simultaneously heating the R-T-B sintered magnet raw materials and the RH diffusion sources. The size of each R-T-B sintered magnet raw material is larger than 1000mm3, and the maximum size is two times of the minimum size among the sizes in three orthotropic directions. Each RH diffusion source