Objective: To explore the mediation effect of eating behavior in the personality obesity association, so as to provide scientific evidence for preventing childhood obesity in China. Methods: This study investigated 1 271 children in September 2018 among Beijing, Changzhi and Urumuqi. By used NEO five Factor Inventory to assess characteristics of personality and used Children Eating Behavior Questionnaire to measure eating behaviors in children. Five obesity related indicators [body mass index (BMI), BMI Z score, waist circumference, waist to hip ratio and body fat percentage] were derived from physical examination. Results: After adjusting for sex, age and region, the standardization scores of conscientiousness were negatively associated with BMI( B= -0.227 , 95%CI =-0.422--0.031), BMI Z score( B=-0.081, 95%CI =-0.158--0.006), waist circumference( B=-0.720, 95%CI = -1.281--0.159), waist to hip ratio( B=-0.004, 95%CI =-0.007--0.001) and body fat percentage ( B=-0.727, 95%CI = -1.293--0.162)( P <0.05). Results from the mediation analysis showed that the associations between conscientiousness and BMI, BMI Z score, waist circumference, waist to hip ratio and body fat percentage were partly mediated through food responsiveness and emotional eating behaviors; with effects ranged from 27.5%-47.1% and 0.9%-18.0%( P <0.05). Conclusion Conscientiousness is associated with lower risk of childhood obesity and food responsiveness and emotional eating behaviors show mediating effect in the association between childhood personality and obesity. Health education should be carried out in time for children with low conscientiousness in order to prevent the occurrence of obesity in the early stage.