Objective: To investigate the oral health status and related factors of 12-year-olds from regions with and without coverage of the National Oral Health Comprehensive Intervention Program in China by means of analysing national data from the 4th National Oral Health Survey. Methods: Data of 12-year-olds participating in the 4th National Oral Health Survey of China were used for statistical analysis. Children who were recruited in the survey completed a dental examination and filled in a questionnaire. Oral health status, pit-and-fissure sealant history, oral hygiene behaviours, sugar consumption habits, status of dental service utilisation, and oral health knowledge were compared between children from regions with and without coverage of the national programme. For the number of decayed, missing and filled permanent teeth (DMFT) and its components, as well as the number of teeth with pit-and-fissure sealants, mean values were statistically tested to see if significance existed between regions covered by the national programme and uncovered regions, whereas caries prevalence and percentage of pit-and-fissure sealants presented were also compared. Results: Data from 27,821 12-year-old children were analysed, among whom 7,726 were from regions covered by the national programme and 20,095 were from uncovered regions. Statistical significance was found in caries experience and activity, pit-and-fissure sealant history, sugar consumption habits, utilisation of dental services and oral health knowledge when compared between the covered and uncovered regions. Prevalence of dental caries and indices for caries experience and activity was lower in regions covered by the national programme than those not covered, while the percentage of pit-and-fissure sealants presented and the number of teeth with pit-and-fissure sealants exhibited higher in the covered regions. This remained the same even if we focused only on the first molars instead of the full dentition. Conclusion: The National Oral Health Comprehensive Intervention Program for Children in China potentially contributed to better oral health status, behaviour and knowledge in 12-year-old children. The expansion and extension of coverage of the national programme was expected to be beneficial for improving oral health status in children, as well as constructing teams of oral and dental workforce and working mechanisms in some underdeveloped regions. Keywords: National Oral Health Comprehensive Intervention Program for Children, oral health status, pit and fissure sealants, 12-year-olds, the 4th National Oral Health Survey