ABSTRACT Objective To investigate the level of serum iron (SI) and serum unsaturated iron binding capacity (UIBC) in healthy adulTSAT in Changsha, and to calculate serum total iron binding capacity (TIBC) and transferrin saturation (TSAT) to establish reference intervals of UIBC, TIBC, and TSAT to provide a basis for clinical diagnosis. Methods A total of 387 healthy adulTSAT ( 167 males and 220 females) were classified into five groups by different age,including 20 to 29，30 to 39，40 to 49，50 to 59 and 60～69 group. The level of serum SI and UIBC were measured by the direct method of phenanthroline assay. And calculate TIBC and TSAT. Verify the reference intervals of serum iron According to the requiremenTSAT of Clinical and Laboratory Standards Institute (CLSI) C28-A3，and establish the reference interval of UIBC 、TIBC and TSAT by nonparametric method．Result The data of serum UIBC TIBC and TSAT were all consistent with normal distribution or approximately normal distribution. Average TIBC was （57.0±6.7）μmol/L (mean ± SD) in 167 males and （57.6±7.1）μmol/L (mean ± SD) in 220 females with no statistical significance (P>0.05). Aerage UIBC was （33.9±8.7）μmol/L (mean ± SD) in 167 males and （37.6±8.6）μmol/L (mean ± SD) in 220 females with statistical significance (P＜0.05). Aerage TSAT was （40.9±12.0）μmol/L (mean ± SD) in 167 males and （35.1±10.1）μmol/L (mean ± SD) in 220 females with statistical significance (P＜0.05). Subjects were compared by age groups ，there were statistical significances among the five age groups in TIBC. But there were no statistical significances between any two group of the five age group in the post hoc analysis. There were no statistical significances among the five age groups in TSAT ,whatever for males and females. There were no statistical significances among the five males age groups in UIBC（P＝0.541） . There were statistical significances among the five females age groups in UIBC（P＝0.022）,but there were no statistical significances between any two group of the five age group in the post hoc analysis. Statistical analysis above indicated that TIBC didn’t need to calculate reference intervals by sex and age groups and UIBC and TAST didn’t need to be grouped by age but need to be grouped by sex to calculate reference intervals. Therefore, the reference range of serum TIBC in healthy adult in Changsha area was 45.2-73.4 μmol/L, the reference interval of serum UIBC was 16.0-54.4 μmol/L for males and 23.4-58.2 μmol/L for females,the reference interval of serum TSAT was 20.9 - 67.1 % for males and 16.6 ~ 54.4 %for females. The reference interval of serum UIBC TIBC and TSAT in healthy adults was established in Changsha area .