Particle-reinforced material is a kind of difficult-to-machine material. In general, it is inefficient if conventional methods are used to shape it, with worse surface quality and serious wear of the cutting tool. In this paper, the machineability when the material is machined by wire EDM is studied. A method of orthogonal design has been adopted to determine the main factors that affect the machining process. The result shows that the electric discharge energy is closely related to machining stability. A good machining effect can be attained when the electrical parameters are properly selected, otherwise, the machining may be unstable resulting in wire breakage.