Abstract: Objective To assess the effect of resin EMBRACE WetBond and glass ionomer GC Fuji Ⅶ as pit and fissure sealant on teeth of children under conditions of limited moisture isolation for 6 months,using QLF. Methods 114 children aged 3 to 5 years old who meet the inclusion criteria were recruited from Chengdu.The subjects were randomized into two groups.Using EMBRACE WetBond and GC Fuji Ⅶ as pit and fissure sealant between two groups.QLF images were taken of each tooth 3 months and 6 months after seal． Results 105 chldren completed the 6 months′ clinical trial,and the number of sealed teeth was 201.The results showed statistically significant differences between sealed teeth of children in two treatment groups in total fluorescence loss of green fluorescence（ΔQ） after seal,3 months and 6 months after seal（P<0.05）,and in total red fluorescence（R）（P<0.01） except in 3 months and 6 months after seal（P=0.191）. Conclusions QLF can effectively evaluate pit and fissure sealant on primary molar teeth,and it can be a monitoring means to prevent tooth decay..