Objective To study the prevalence and risk factors of caries among 5-year-old children in Guangzhou, in order to provide theoretical evidence for developing scientific and effective interventions.Methods Data of 5-year-old children in “Sampling survey on oral health epidemiology of children in Guangzhou” were collected and compared between 2008 and 2015. And the influencing factors of dental caries in 5-year-old children were analyzed.Results The prevalence of caries, mean dmft and filling rate in children aged 5 years in Guangzhou increased from 56.11%, 3.04 and 3.01% in 2008 to 76.78%, 5.47 and 4.05% in 2015, respectively. In both 2008 and 2015, caries prevalence and mean dmft in rural children (2008:78.89%, 5.33; 2015:86.05%, 6.91) were higher than those of urban children (2008:48.52%, 2.28; 2015:74.22%, 5.07). However, the filling rate of rural children (2008:1.04%; 2015:1.15%) were lower than that of urban children (2008:4.55%; 2015:5.14%). And there were no significant differences on caries prevalence, mean dmft and filling rate between boys and girls(all P>0.05). In 2015, 72.06% of caries occurred in the upper middle teeth and the first or second molars, and 70.31% of the total caries number of teeth occurred in 32.16% of the children. Multivariate conditional Logistic regression showed that habit of eating sweets before bedtime (OR=1.45, 95% CI:1.08~1.94), starting to brush teeth after 2 years old (OR=1.41,95% CI:1.06~1.86), lower education background of parents (OR=1.58,95% CI:1.19~2.11) and poor family economic status (OR=1.81, 95% CI:1.23~2.67) were risk factors for caries among children.Conclusion The prevalence of caries among 5-year-old children in Guangzhou is serious, showing an upward trend and low treatment rate. Therefore, the anti-caries and treatment measures should be adopted to reduce the incidence of caries in children.