Objective: To study the relative translucency of 3 all-ceramics system core material, including Vita In-Ceram Alumina, Vita In-Ceram Zirconium and Ivoclar Vivodent Empress II. Methods: The visible light transmittance of all samples was determined with spectrophotometer. Results: The relative translucency of dentin and opaque dentin was between 0.5958 and 0.8336, that of 3 core ceramic ranged from 0.8089 of Emp ress II to 1.00 of In-Ceram Zirconium. Conclusion: The relative translucency of 3 core material was significantly different. There was a decreasing range as Empress II > In-Ceram Alumina and In-Ceram Zirconia.