Abstract: ［Abstract］Objective　To investigate the status of the bone mineral density（BMD）of children in child health service clinic，to provide reference for the proper period and gender for prevention of the defection of insufficient BMD. Methods　Form march 2014 to may 2015 ，bone mineral density of 2519 healthy children in Kunming children's hospital was tested by using sunlight Moistens Tm-Tooo p type of quantitative ultrasound bone density doctor. The BMD values were analyzed according to the age and gender groups. Results（1）SOS gradually increased with the age（P＜0.05）. （2）The defection rate of insufficient BMD was higher among girls than among boys. （3）The critical period of insufficient BMD was the group of 0 to 6 months，the second was the group of 7 to12 months. Conclusions（1）Children less than 1 year of age is the main crowd prevention bone deficiences；（2）Prevention of bone deficiences need early intervention,especially in the month of birth 6.