Objective:To evaluate the effects of surface modification with different concentration silica sol through sol-gel processing on bond strength between dental zirconia ceramic and resin cement. Methods:Silica coating was prepared by colloidal silica sol with concentrations of 20%,30%,40% on dental Zirconia ceramic. 32 discs zirconia ceramic specimens were fabricated and randomly divided into four groups respectively after polishing and sandblasting.The ceramic surfaces of different groups were received different treatments:(1)silane couple agent;(2)20% silica coating and silane couple agent;(3)30%silica coating and silane couple agent;(4) 40% silica coating and silane couple agent. Each ceramic block was bonded to light curing composite resin. All samples were stored in distilled water at 37 degrees for 24 h before a shear bond test to measure the bond strength of the resin cement to the ceramic surface. Scanning electrical microscopy (SEM) and energy depressive spectrum (EDS) were used to analyze the silica coating. Results:Contents of surface silicon increased after modification with silica coating prepared by sol-gel method. Bond strengths of groups with silica coating were significantly higher(P