Background: In parallel with the increased prevalence of childhood overweight and obesity, the rate of eating out in China has increased dramatically in recent years. The purpose of the study was to explore the association between frequency of eating out with overweight and obesity among Chinese children.Methods: The representative sample of Chinese children aged 6-17 years (7685 boys; 7576 girls) was recruited from Chinese National Nutrition and Health Survey (CNNHS) in 2010-2012. Frequency of eating out was collected by interview-administered questionnaire and categorized as: less than once per week, once and twice per week, and three times or more per week. Height and weight were measured (body mass index was consequently calculated). Results:The prevalence of eating out among Chinese children aged 6-17 years old was 23.2%. Children who ate out 0, 1-2, ≥3 times per week were accounted for 76.8%, 10.9% and 12.3% respectively. Findings revealed that eating out three times per week or more was statistically significant associated with higher prevalence of overweight and obesity among boys (OR=1.20,95CI:1.04-1.38) compared with those ate out less than three times per week. However, no significantly association was observed among girls (OR=0.91, 95CI:0.78-1.01). In additional, Younger children, rural children, children from low income family, those with leisure exercises (certain physical activities regularly carried out such as swimming, walking, running, equipment fitness), leisure time sedentary behaviors (LTSB)(>2h/d) were relatively more likely to eat out. Conclusions: The results illustrated that eating out three times or more had a significantly positive effect on overweight and obesity among boys in China.