Objective: To evaluate the cost-effectiveness of comprehensive oral health care for severe early childhood caries (S-ECC) in urban Beijing, China. Methods: A randomised cluster sampling method was used to select 187 children aged 3 to 5 years with S-ECC from two kindergartens in urban Beijing. Comprehensive oral health care and questionnaires for the parents/guardians were provided to the test group, while an oral health examination and questionnaires for the parents/guardians were provided to the control group. Data were collected and a Markov model was established for a cost-effectiveness analysis. Results: One year later, 614 RMB yuan and 184 RMB yuan were needed for the control and test group, respectively, to reduce one average decayed tooth. The cost for the test group was continuously lower than for the control group during the 4-year simulation. The cumulative cost for the test group was lower than for the control group when the model was circulated for more than 1.5 years. At this time, the change of decayed teeth was stable in the test group. Conclusion: Comprehensive oral health care had extraordinary cost-effectiveness for S-ECC. The optimal time to process S-ECC may be after 1.5 years. Keywords: comprehensive oral health care, severe early childhood caries (S-ECC), cost-effectiveness analysis, Markov model