Objective: To analyze the epidemiological characteristics and related factors of obesity in children aged 3-6 years old in Hebei Province, and to provide a reference for childhood obesity prevention and control strategies. Methods: A total of 6 034 children aged 3-6 years were randomly selected from 11 cities in Hebei Province for physical examination and questionnaire survey. Results: The prevalence of obesity in 3-6 year old boys and girls in Hebei Province were 23.00% and 17.48 %, which differed significantly ( χ 2=28.51, P <0.01); The prevalence of obesity was higher in rural areas and children with ethnic minorities ( 20.06 %, 21.68%) than that of urban are and Han children (19.97%, 20.09%), with no significant differences ( χ 2= 0.01 , 0.78, P ＞0.05). Multivariate Logistic regression analysis revealed that boys( OR =1.45), birth weight no less than 4 000 g ( OR =2.80), high fat food consumption at least 3 times a week （OR =1.64), carbonated drinks consumption at least 3 times a week ( OR =4.71), insufficient fruits and vegetables consumption ( OR =1.22), physical activities less than 2 hours per day ( OR =1.82), maternal obesity ( OR =2.0), and lack of physical exercise of fathers ( OR =1.95) were significantly associated with higher risk for obesity among young children in Hebei Province ( P <0.01). Conclusion The prevalence of obesity among children aged 3-6 years in Hebei Province is at a high level at present. Many factors contribute to this epidemic such as genetics, poor diet and living habits. Promotion of healthy eating and lifestyle, as well as dissemination of reliable knowledge about childhood obesity are greatly needed.