Abstract: Objective To analyze the eruption and caries prevalence of first permanent molar in Chinese children aged 7-9 years for the determination of suitable age of pit and fissure sealant.Methods Data of oral examination among 560 121 children between 2014 and 2015 were collected and analyzed.Results The complete eruption rate of first permanent molar among the children aged 7, 8, and 9 years were 79.53%, 89.84%, and 93.81% and the caries prevalence were 12.18%, 16.83%, and 19.61%, respectively;the two rates increased with the increment of age among the children and the two rates were higher among the girls than among the boys.Caries often occurred on occlusal surface of upper and lower teeth, buccal surface of lower teeth, and lingual surface of upper teeth.Conclusion The complete eruption rate of first permanent molar is high among 7-9 years old children and the prevalence of first permanent molar caries is also high among the children, suggesting that pit and fissure sealant should be carried out at early age among the children.