Microwave sintering is a new sintering technology developed in the middle to late period of the 1980’s, which is characterized by fast densification for ceramic materials[1]. In recent years, microwave heating has been well employed in the field of sintering and joining of ceramics as a result of its advantages against conventional methods. These ceramic materials include oxides, mixed oxides, non-oxides, composite ceramics, etc[2]. In addition, because ceramics have low thermal conductivities and are processed at high temperatures, many researchers have attempted to take advantage of volumetric heating for sintering, chemical vapor infiltration (CVI), and pyrolysis of polymeric precursors[3]. Now it has been found that the microwave sintering can also be applied as efficiently and effectively to thermistor ceramics as well as many other ceramics. This chapter compares advantages of microwave sintering with conventional sintering and presents some applications in thermistor ceramics.