Objective To measure the translucency parameter（TP）, masking effect（ME）, and contrast ratio（CR） of opal porcelain of Ceramco, Shofu, Noritake, and Vita, and to compare the correlations among the three transmission parameters, in order to provide reference for selecting opal porcelain correctly. Methods The color of specimens was measured according to CIE L*a*b* under different background and reflectance mode with a Color- Eye 7000A spectrophotometer. The color difference, TP, and ME value were calculated. Within 400- 750 nm spectra, the ratio of light reflectance was measured, and CR was also calculated. The data was compared by ANOVA and SNK- q test （α=0.05）. The correlation and multiple linear regression between TP, CR, and ME were analyzed（α=0.05）. Results There were statistical difference with different shade of the same brands （P
