Ojective To evaluate the prevention effects of a school-based pit and fissure sealant program to the dental caries of the first permanent molar of the schoolchildren in Xincheng district of Xi'an,China. Methods By the method of retrospective cohort study,the class took as a whole group to make random cluster sample and 760 children aged 10~12 years old,were divided into sealant group (464 children) and control group (296 children) according to whether or not to participate in pit and fissure sealant program,their general demographic information,oral hygiene habits,knowledge,attitude,etc were surveyed.History oral examination results of them were used to evaluate the risk of dental caries.The FPM caries situation was compared between two groups,and the pit and fissure sealants reserved were checked in the sealant group. Result With the one-time sealant application,follow-up time was (2.63±0.09) years,The complete sealant retention rate of occlusal surfaces was significantly higher than that of buccal/lingual surfaces (62.9% vs 18.8%,χ²=184.64,P=0.000).The caries/restored rate on buccal/lingual surfaces was significantly higher than that of occlucal surfaces (10.4% vs 6.2%,χ²=7.89,P＜0.01).The odds ratio for dental caries was 6.11(95%CI=4.28～8.73)compared between no sealed occlucal surface and sealed ones.Unconditional logistic regression analysis showed that sealant retention was a remarkable protect factor for the FPM(AOR:0.07,95%CI:0.03～0.17).Using direct standardization to control the different caries risk ratio of children in two groups,the caries rate of the first permanent molar in sealant group and in control group was 12.4% and 17.6% respectively,the reduction of attack rate was 29.6%. Conclusion The school-based pit and fissure sealant program had prevent effects on dental caries of schoolchildren in Xincheng district of Xi'an.