Objective To analyze the changes of bone mineral density（BMD） in toddlers aged 1~36 months with normal growth and development at different developmental stages，and to establish the reference database of ultrasound BMD in toddlers aged 1~36 months in western Fujian province.Methods 7485 toddlers aged 1~36 months with normal growth and development were divided into 6 groups，including 1~3 months，4~6 months，7~9 months，10~12 months，13~24 months，and 25~36 months.The BMD parameters were measured by ultrasound bone sonometers，the changes of BMD parameters（speed of sound（SOS），Z value）and the detection rate of BMD deficiency in toddlers of different month and sex were compared.Multiple linear regression was used to analyze the related influencing factors of BMD.Results In terms of BMD parameters，SOS of toddlers decreased gradually at 1~3 months and increased gradually after 3 months. girls’ SOS was higher than boys’ at 1~3 months and lower than boys’ at 25~36 months，with statistical significance（all P＜0.05），and there was no statistical significance in SOS between boys and girls at the remaining age groups； At 1~24 months，boys’ Z value was greater than girls’，and the detection rate of BMD deficiency of boys was lower than girls’（P＜0.05），At 25~36 months，there was no significant difference in Z value and the detection rate of BMD deficiency in boys and girls； Compared with the existing BMD databases，up to 51.29% of toddlers had BMD deficiency at 1~3 months，and the detection rate of BMD deficiency was higher than 10% at 4~9 months.Multiple linear regression showed that SOS was positively correlated with age and body length，and negatively correlated with body mass and sex； Z value was positively correlated with body length and sex，and negatively correlated with body mass（all P＜0.05）.Conclusion BMD of toddlers increases with age and body length.1~9 months is the high incidence month of BMD deficiency. Strengthening the early screening of BMD in toddler at these months can help distinguish toddler at high risk of BMD deficiency in local area，early detection and early treatment of toddlers with BMD abnormalities，and improve the bone health of toddlers in western Fujian province.