Objective To analyze the relationship between bone mineral density (BMD) of infants over 6 months of age and exclusive breastfeeding and calcium nutrition guidance during pregnancy in Baoding area, and to provide evidence for clinical application. Methods A total of 308 infants over 6 months of age were selected from Baoding Maternal and Child Health Hospital from January 2020 to January 2023, and their BMD was measured by ultrasound. The level of 25 (OH) D3 in subjects' blood was detected. spearman correlation test was used to analyze the correlation between infant bone mineral density and exclusive breastfeeding and calcium nutritional guidance during pregnancy, and logistics regression model was used to analyze the independent factors affecting infant bone mineral density. Results The level of serum 25 (OH) D3 in normal BMD group was significantly higher than that in abnormal BMD group (P<0.05). The rate of exclusive breastfeeding and the guidance rate of calcium nutrition during pregnancy in normal BMD group were significantly higher than those in abnormal BMD group (P<0.05). There was a significant positive correlation between different bone mineral density and exclusive breastfeeding and calcium nutrition guidance during pregnancy (P<0.05). Serum 25 (OH) D3 level, exclusive breastfeeding rate and calcium nutritional guideline rate during pregnancy were independent protective factors for bone mineral density (P<0.05). Conclusion Bone mineral density (BMD) of infants over 6 months of age is positively correlated with exclusive breastfeeding and calcium nutrition guidance during pregnancy, and exclusive breastfeeding and calcium nutrition guidance during pregnancy are independent protective factors affecting BMD of infants over 6 months of age.