BackgroundPrevious research has documented mental health status among rural-to-urban migrant children (labeled as “migrant children” henceforth) and urban children. However, the findings remain unclear. In addition, far less attention has been paid to rural children’s psychological outcomes. The purpose of this study was to compare mental health status among migrant, urban and rural school-age children in Guangdong Province, China.MethodsThis was a cross-sectional study involving 372 migrant, 254 urban and 268 rural children selected respectively from 3 private schools, 4 public schools and 2 village schools in Guangdong Province, China. Participants provided their socio-demographic information and completed the Strengths and Difficulties Questionnaire (SDQ) to assess mental health. One-way analyses of variance (ANOVAs) and Bonferroni post hoc test were used to evaluate SDQ scores differences. A multiple linear regression analysis was conducted to measure mental health differences among children after controlling for socio-demographics. Chi-square analyses were used to assess differences in the prevalence of mental health problems among children.ResultsBonferroni post hoc test showed that migrant and rural children reported significantly higher scores than urban peers in emotional symptoms, hyperactivity/inattention and total difficulties score (p < 0.01). In addition, migrant children reported a higher peer problems score compared to urban children (p < 0.001). In multiple linear regression analysis, rural and migrant children reported significantly a higher total difficulties score than urban children (p = 0.046 and 0.024, respectively). Additionally, female gender, having insurance, seldom communicating with parents, and higher monthly household income were negatively associated with a higher total difficulties score. Conversely, children’s father with secondary education was positively associated with a higher total difficulties score. The prevalence of mental health problems among rural, migrant and urban children were 26.5, 18.8 and 15.0% (χ2 = 11.41, p = 0.003), respectively.ConclusionsRural and migrant children reported poorer mental health than urban children. Female gender, having insurance, seldom communicating with parents, and higher monthly household income were associated with better mental health of children. However, children’s father with secondary education was associated with poorer mental health of children. Given the different effects of socio-demographics, further support might be provided accordingly to improve the mental health of school-age children.