The aim of this study was to analyze the microstructure and to observe the surface reactivity of a composite system composed of two kinds of zirconia/alumina (Z/A) composites and Vita alpha glass-ceramic, which would satisfy the biocompatibility and strength requirements for dental applications. Two zirconia/alumina composites defined as specimen A and B were used as the substrate of fixed partial denture, while commercial Vita alpha glass-ceramic as the coating-glass.From the experiment we can find the following results. Zirconia particles migrated into grain boundaries and located at three or four grain junctions of alumina particles. The crack pattern is consistently transgranular for the zirconia grains, whereas it is intergranular for alumina grains. The mechanical properties of the composite with 66.6wt% zirconia was superior to that of 33.3wt% zirconia-composed composite, while the homogeneous bond between Vita alpha glass-ceramic and Z/A composites are distinct. Therefore, this system composed of Z/A composites and Vita alpha glass-ceramic would satisfy matching properties of dental requirements and it has a great future to be used as all-ceramic restoration materials.