Purpose: To assess the effect of oral comprehensive healthcare on the prevalence of early childhood caries in urban areas of China. Materials and Methods: A total of 398 children aged 4–5 years from six different kindergartens in Qingdao were recruited to participate in a 1-year single-blind randomised controlled clinical trial. They were randomly assigned into either an experimental group (187 children) or a control group (211 children). The experimental group received comprehensive oral healthcare including oral health examinations, oral health education for children and their guardians, and local fluoride application and dental treatment, whereas children in the control group only received oral health examinations twice a year. The children's parents finished a comprehensive oral health questionnaire before and after the experiment. After a year, the oral health status of two groups of children was statistically analysed to determine the effect of oral comprehensive healthcare on early childhood caries. Results: After 1 year, the numbers of decayed teeth (dt), decayed tooth surfaces (ds), filled teeth (ft), and filled tooth surfaces (fs) in the experimental group were significantly lower than the control group (p <0.001). The dmft and dmfs were also significantly different between the two groups (p <0.05). Statistically significant differences were additionally shown in oral hygiene habits and eating habits of both the children and their parents in the two groups compared with 1 year before (all p <0.001). Conclusion: Implementation of comprehensive oral healthcare measures both prevents and reduces early childhood caries.