A new process of machining the TiN/Si3N4 nanocomposite ceramics using wire electrical discharge machining is proposed in this paper. The process is able to effectively machine a large surface area on the TiN/Si3N4 nanocomposite ceramics with good surface quality and low cost. The effects of machining conditions on the material removal rate, and surface roughness have been investigated. The surface microstructures machined by the new process are examined with a scanning electron microscope (SEM). The results show that the TiN/Si3N4 nanocomposite ceramics is removed by melting, evaporation and thermal spall. The experimental results indicate that the cutting speed (material removal rate), the surface roughness and the width of the slit of cutting test material significantly depend on experiment parameters. An appropriate servo voltage, a short pulse-on time, and a short pulse-off time, which are normally associated with a high cutting speed, have little effect on the surface roughness. During experiments, parameters such as open circuit voltage, pulse duration and dielectric fluid pressure were changed to explore their effect on the surface roughness.