Objective To find the features of children body component aged 3 to 12 years old and to explore the influence of different body component to bone age. Method The cross-sectional study was conducted for the children aged 3 to 12 years old in the outpatient visit of our department and tested by physical exam,body component analysis and bone age evaluation during April 1^st in 2012 and December 31^th 2013. Results A total of 1 351 children between 3 to 12 years old were selected,748 were male,603 were female and their ratio was 1.24∶1.According to the order of the children in growth retardation,low body weight,overweight and obesity,the incidence were 17.25%,12.95%,11.18% and 7.62%.The bone age in different age group was lower than actual age,and bone development retardation incidence was 4.66%,where as partial retardation incidence was 18.65%.The mal-contents ratio of skeletal muscle,bone mineral matter and mineral salt was 44.19%,37.38% and 37.16%,where as over-contents ratio of fat was 23.24%.The independent variable playing positive roles for the advanced bone development were fat thickness of arms,body fat mass,total body weight and BMI.The factors playing negative roles for the advanced bone development were fat thickness of legs,skeletal muscle mass and bone mineral mass. Conclusion Carrying out rational diet,adequate exercise,avoidance of weight gain(especially fat gain),adequate praeparatum supply of vitamin and mineral matter can defer bone development effectively,and it is possible to procure taller ultimum height.