It's difficult to determine some egg quality traits in commercial poultry farms.Therefore, this study was conducted to find linear regression between external egg traits and effect of hen age on some external characteristics of eggs in Lohmann Brown- Classic hen. A total of 120 hens were housed in battery cages include four lines from 24 to 41 weeks of hen's age. In this experiment we measure external physical characteristics (egg weight (g), egg shape index, egg strength (kg/cm2), specific gravity, shell thickness (mm), egg surface area and unite of surface shell weight (mg/cm2) were study. Results showed that relations between egg shape index with egg width positive, but negative with egg weight and length (p<0.05). Otherwise, the phenotypic relations values of egg weight and egg shell traits showed highly significant (P<0.01) positive with egg weight specific gravity, shell percentage, shell thickness and shell strength. All external egg quality characteristics increased with the increase of hen's age. Egg shape index, Surface area, and specific gravity, shell thickness and unit surface area were increased significantly (p<0.05) with the increase of hens age. While percentage of egg shell decreased for older hen age. The egg strength ranged between 1.00 –1.20 (kg/ cm2) during the experiment period.