Sintered NdFeB permanent magnet is widely used because of its excellent magnet property. But there is few report of machinbility of it. This paper presents an experimental investigation of the machining characteristics of sintered NdFeB permanent magnet using a combination process of electro-discharge machining (EDM) with ultrasonic machining (USM). The EDM / USM machining mechanisms are integrated to improve the machining efficiency. During the experiments, concentration of abrasive in the dielectric fluid is changed to explore its effect on the material removal rate (MRR). MRR of EDM /USM, conventional EDM and tool vibration aided EDM are compared, REWR and machined surface characteristics are also compared between them. From the experimental results, it is concluded that the combination EDM/USM process can increase the MRR and decrease the thickness of the recast layer. In the combination process, an appropriate abrasive concentration can improve its machining efficiency.