Abstract: The three-phase ceramic composite(Ti,Zr)N has been prepared by high temperature nitridation and anneal of an ultra pure TiZr alloy. This result is different from the previous works which had concluded that the titanium nitride and zirconium nitride could only form a single solid solution with complete miscibility through all the composition range. The techniques including X-ray diffraction (XRD),energy-dispersive X-ray spectroscopy (EDS) and high resolution transmission electron microscopy (HRTEM) have been used to characterize the crystal structures and the chemical composition of the composite. The XRD analyses have given the information about the structural properties of the material (3 phases,all having face centered cubic structure with different lattice parameters).The chemical microanalyses have given the relative atomic percentage ratios of the metailic elements in each phase as well as their approximative chemical expressions. In combination with HRTEM,it was finally established that the phase with the biggest lattice parameter is rich in Zr,the phase with the smallest lattice parameter rich in Ti,and the phase with a middle lattice parameter has nearly equalatomic metallic elements.