OBJECTIVES: To evaluate the preventive effectiveness and cost-effectiveness of pit and fissure sealant for prevention of dental caries among school-age children from four provinces in China. METHODS: The data were collected in a three-year dental prevention programme among school-age children in piloting schools of Hebei, Guangxi, Jilin and Liaoning of China. Health outcomes were measured as DMFT and the prevalence of caries. DID (difference in difference) model was used to evaluate the net effect change of pit and fissure sealant by controlling other cofounding factors. From a societal perspective, cost-effectiveness analysis was used to evaluate the pit and fissure sealant caries and Sensitivity analyses were conducted to assess the robust of results. RESULTS: Comparing to no intervention, pit and fissure sealant caries could reduce DMFT with 0.366 and drop the prevalence of caries with 75.1% (p <0.001). In the analysis of cost-effectiveness, the incremental cost per DMFT avoided over the three-year period was RMB149.29 and the one for a percentage point of the prevalence of caries was RMB 4.50.  CONCLUSIONS: Pit and fissure sealant is effective in preventing the occurrence of dental caries in school-age children. Compared to control group, pit and fissure sealant is more cost-effectiveness.