Abstract: The purpose of this study was to study the effects of iron and VA on serum protein metabolism in commercial generation of Henlan Brown laying hens. A total of 432 healthy hens 26-week-old were randomly divided into 6 groups with 6 replicates in each group. Completely random experiment design method of 3×2 （iron×VA） was adopted, and the iron content in diet was 0, 30, 60 mg/kg and the VA content was 4 000 and 8 000 IU/kg, respectively. Feeding experiment was conducted for 8 weeks from 27 weeks age, and the serum total protein content and serum urea nitrogen content of the laying hens were measured at 30^th and 34^th week of age, respectively. The results showed that the interaction of dietary iron and VA had no significant effect on serum total protein concentration of 30-week-old and 34-week-old layers （P〉0.05）; the addition level of dietary VA had a significant effect on serum total protein concentration of 30-week-old layers （P〈0.05）, and the high-level dietary VA （8 000 IU/kg） was significantly higher than the low-level dietary VA （4 000 I U/kg）. The interaction between dietary iron and VA had no significant effect on serum urea nitrogen concentration of 30-week-old and 34-week-old laying hens （P〉0.05）; the addition level of dietary VA had a significant effect on serum urea nitrogen concentration of 30-week-old laying hens （P〈0.01）, and the high-level dietary VA （8 000 IU/kg） was significantly lower than the low-level dietary VA （4 000 IU/kg）. In conclusion, adding VA to diets can improve the protein metabolism process of laying hens.