Abstract: Calcium（Ca） is one of the most important nutrients for poultry to lay eggs and maintain bone health. In order to better understand the effect of calcium on bone microstructure and element concentration of laying hens, 180 Roman white laying hens were randomly divided into control group and low calcium diet group. The dietary calcium concentrations were 3.37% and 1.50%, respectively.Laying hens were housed in enriched cages, each group had six replications and each replication had15 laying hens. The trial period was 20-37 weeks. Bone samples were collected at 25, 29, 33 and 37 weeks of age to measure bone mineral density, bone microstructure parameters and bone element content. The results showed that the percentage of normal keel in low calcium group was lower than that in control group, the keel deviation rate at 37 weeks was 31.25%, and the fracture rate was56.25%. The keel microstructure parameters of TV, BV, BV/TV, Conn. D., Tb.Th, Tb.Sp, BS, BS/BV,DA, BMD were significantly different in low calcium group compared with the control group（P＜0.05）,that was the TV, Conn.D., Tb. Sp, BS, BS/BV, BMD decreased, and BV, Tb.Th, DA increased. The contents of K, Fe, Cu, Sr, Mo, Mn, Zn, V, Se, Tl and Pb in keel bones of laying hens in low calcium group increased（P＜0.05）, and the contents of Ca, Ni, Li and Hg decreased（P＜0.05）. Therefore,feeding low calcium diet during laying period affects the growth and metabolism of bone, changes the bone density, microstructure and element homeostasis of keel bones, impairs the keel bone quality and the health of laying hens.