ObjectiveTo investigate the prevalence and risk factors of sever early childhood caries (SECC) among 3 to 5 years old children of Uyghur and Han in Kashi city, and to provide scientific basis for the establishment of oral hygiene policies for caries prevention and diagnostic among children. MethodsAccording to the basic methods of Third National Oral Health Investigation in 2005, a stratified multistage cluster randomly sampling design was applied. The deciduous caries of 893 Uyghur and Han children aged from three to five in ten kindergartens of Kashi city were clinically examined. Data were collected by questionnaire from their parents, and the result analyzed using SPSS 17.0 software. ResultsThe caries prevalence rate of primary tooth was 74.69% and the total prevalence of SECC was 39.19%. The risk factors for SECC include lower age (OR=1.537, 95% CI 1.132 to 2.086, P=0.006), the more frequencies of drinking coke (OR=1.448, 95% CI 1.008 to 2.080, P=0.045), eating fruits (OR=1.840, 95% CI 1.347 to 2.512, P=0.000), drinking milk (OR=1.794, 95% CI 1.311 to 2.456, P=0.000), and before bedtime eating or after brush eating (OR=1.833, 95% CI 1.199 to 2.802, P=0.005), as well as the higher age of starting brush (OR=2.053, 95% CI 1.448 to 2.910, P=0.000). The protective factors for SECC include the more frequency of brushing (OR=0.612, 95% CI 0.445 to 0.844, P=0.003), and higher household income (OR=0.526, 95% CI 0.423 to 0.654, P=0.000). ConclusionThere is a high prevalence of SECC in Kashi city. It is necessary to strengthen the prevention and education activities, and perform early preventive works for caries disease of children.