Abstract: Objective To study the law of basal thickness and translucency of two brands of translucent zirconia ceramics and IPS Empress II glass-ceremic so as to provide clinical reference for chosing and fabricating all-ceremic basal material aesthetically. Methods Four groups of square-shaped specimens (12 mm in length and 0.4 ,0.6, 0.8, or 1.0 mm in thickness) made of two kinds of translucent zirconia ceramics separately and another four groups of square-shaped Empress II glass-ceramic specimens (12 mm in length and 0.6, 0.8, 1.0, or 1.2 mm in thickness ) were fabricated, five disks per group. The relative translucency of each specimen was measured with a spectrophotometer after polishing. Results There were no significant differences in the relative translucency among three all-ceramic core materials in the same thickness (P>0.05). Increasing the thickness resulted in decrease of relative translucency. When the thickness of zirconia ceramic core materials was 0.4mm, the relative translucency was the best, which showed significant difference with other groups in the same material (P<0.05). Conclusion The translucency of all-ceramic core materials decreases along with the increase of thickness. The translucency of zirconia ceramic core materials is best in the thickness of 0.4mm, and the translucency of zirconia ceramic core materials in the thickness within 0.6~1.0 mm is similar to that of Empress II ceramic glass-ceramic material.