Abstract: Upper arm circumference is an useful and convenient index for evaluating the nutritional status and growth of young children. We mersured upper arm circumference, weight and hight in 902 school-age children (462 males 440 females). They are living in Beijing. The range of age in this group was 7 to 12 years old. The upper arm circumferences of children in this age group ranged from 16cm to 20cm. Upper arm circumference grows gradually with increasing of age and there is a close correlation between upper arm circumference and weight. The advantages of using the uppr arm circumference measurement is that it is time-saving and easy to perform, requires no expensive or sophisticated equipment.