This study was conducted to evaluate the efficiency of dietary varying levels of nano di-calcium phosphate (NDCP) on eggshell quality [total thickness (EST), mammillary layer thickness (MT), and mammillary density (MD)] egg mineral contents, bone breaking strength, serum calcium and phosphorus concentrations and calcium (Ca) and phosphorus (P)  retention in old laying hen. Therefore, one hundred and eighty brown LSL hens at the age of 52 weeks of age were used for 12 weeks at the end of their production period. Hens were divided into four equal groups, 45 birds/group with nine replicates each. The treatments were as follows: Group (1): basal diet (control); Group (2): basal diet + 200g NDCP/ ton; Group (3): basal diet + 400g NDCP/ ton; and Group (4): basal diet + 800g NDCP/ ton.  Results detected that serum Ca and P concentration, tibia fresh weight, tibia ash, tibia Ca, Ca and P retention were significantly increased stuck with the increase in NDCP supplementation level up to 400 g / ton and tend to decrease after that.  Furthermore, Yolk mineral content (Ca and p) accumulation was significantly decreased with increasing NDCP levels. There were no significant differences in tibia breaking strength and tibia P with the supplementation in comparison with the control group. Eggshell thickness and breaking strength increased parallel to the increase in NDCP levels due to the increase in palisade layer and mammillary layer. In conclusion supplementation of NDCP up to 400 g/ ton to layers diet may be help in solving the problems of egg shell weakness at the end of egg laying season or old hen production.