Objective:To analyze the prevalence of goiter among children aged 8 to 10 years old in Beijing and study the influencing factors of goiter in children.Methods:In 16 districts of Beijing, each district was divided into 5 sampling districts according to east, west, south, north and middle locations in 2018. One town/street was selected from each sampling district, one primary school was selected from each town/street, and 40 non-boarding students aged 8 to 10 years old were selected from each primary school. The size of thyroid was measured by B-ultrasound method, the volume of thyroid was calculated and whether goiter or not was determined according to the "Diagnostic Criteria for Endemic Goiter". Random urine samples were collected, urinary iodine was detected by arsenic-cerium catalytic spectrophotometry. Height and weight were measured, body mass index (BMI) was calculated, and the correlation of thyroid volume with height and weight was analyzed.Results:A total of 3 268 children were surveyed, in which 154 children with goiter; the goiter rate was 4.7%. The goiter rate in girls [5.7% (93/1 641)] was higher than that in boys [3.7% (61/1 627), χ 2 = 6.694, P < 0.05]. The goiter rates of children aged 8, 9 and 10 years old were 4.3% (15/346), 5.5% (85/1 534) and 3.9% (54/1 388), respectively, there was no significant difference between the ages (χ 2 = 4.544, P > 0.05). The median of urinary iodine in children was 175.3 μg/L, which was in an iodine appropriate level. The thyroid volumes of children aged 8, 9 and 10 years old were positively correlated with height and weight ( r = 0.143, 0.225, 0.323, 0.338, 0.321, 0.346, P < 0.01). Conclusion:The goiter rate of children in Beijing is high, children's thyroid volume is greatly affected by height and weight, and it is recommended to consider the influence of height and weight when study the diagnostic criteria of children's goiter.