he fracture behaviour of the sintered NdFeB permanent magnetic materials and the composition of phases on grain plane and grain boundary interface have been studied. It is shown that the fracture behaviour of the NdFeB magnets appear mainly intergranular facture and the grain boundary appears O-rich and Nd-rich. It is suggested that the intergranular Nd-rich film with oxygen located on the grain boundary is the main cause of the intergranular fracture of the magnets. The ways to strengthen the NdFeB Permanent magnetic materials have also been proposed.