【Objective】 To investigate the relationship between the height of development and ultrasound bone density of infants, and discuss the deficiency of bone mineral substance in the development of infants, then provide the basis of taking precautions against premature rickets. 【Methods】 The investigation was conducted in 531 6-month-old infants who were selected by stochastic monitoring method in physical examination of outpatient clinic from January 2009 to February 2010, the way was to measure the SOS value of infants' tibial by ultrasonic bone analyzer of Aonuo BMD-1000C of America, and compare with Z value(Z value=(measuring value-mean value)/ Standard deviation of mean value of different age), so could show the bone mineralization situation of infants who be measured in groups of same age. 【Results】 The z value of 6-month infant' bone density had remarkable difference or obvious difference between the low-grade or above average and other grades of heignt evaluation(P all＜0.05). the gradus of the relationship between the positivity rate of Z value of 6-month infant' bone density and the grades of heignt evaluation was average +> above average> average-> below average> superior>low grade. 【Conclusions】 Screening of bone density in priority of such infants whose heignt evaluation was low grade, average and above average, so could maintain level of bone mineral substance in effect and avoid deficiency of bone calcium during the development, taking precautions against premature rickets.