Abstract: Objective To study the dietary habits of first grade school-age children and to investigate their correlation with body mass index in Shenzhen.Methods According to the principle of stratified cluster sampling,33 primary schools were selected in Shenzhen in 2016,and all the first grade students in the primary schools were surveyed.A total of 6 733 questionnaires were issued and the effective number was 6 089.The parents of self-administered questionnaires carried out to ask for a total of 14 kinds of food intake frequency,and to analyze the dietary behavior.Multiple linear regression models were used to analyze the association between dietary behaviors and BMI values in children.Results The overweight rate of the first grade male students in Shenzhen was 10.8%,the obesity rate was 15.1%,the overweight rate of female students was 8.9%,and the obesity rate was 9.1%.The overweight and obesity rate of male students was higher than that of female students(x2 =6.587,43.747,P<0.01).And the overall rate of obesity is higher than overweight.A total of 5 dietary patterns were extracted:high-fat and high-sugar habit,prudent habit,high protein habit,vegetables and fruits habit,and tonic habit.The variance contribution rates of the five dietary patterns was 24.47%,17.04%,7.56%,7.02%,6.89%,and respectively the five dietary habits totally reflect 62.92% characteristics of the 14food-groups.High-fat and high-sugar habit may increase the risk of overweight and obesity,relatively prudent habit is a protective factor for overweight and obesity.Conclusion There are different dietary patterns and characteristics among school-age boys and girls in Shenzhen.High-fat and high-sugar habit is the main dietary behavior,and it is related to obesity.Active measures should be taken for early intervention.