Abstract: Objective　To evaluate the performance of enzymatic method for serum sodium ion determination.  Methods　　The accuracy，precision，off cap stability，linearity，correlation with ion selective electrode method，recovery rate and anti-interference were evaluated by the reagent of enzymatic method for sodium ion determination.  Results　The coefficient of variation (CV) was<2%. Calibration period reached 5 d. Accuracy met Randox′s quality control. Linearity scope was 100-160mmol/L. Coefficient of correlation (r) was 0.989 9, and enzymatic method was correlated well with ion selective electrode method. The recovery rate was 100.9%. No interference appeared when bilirubin≤600 μmol/L，triglyceride≤20 mmol/L，vitamin C≤0.5 g/L，hemoglobin≤10 g/L，ammonium ion ≤25 mmol/L，potassium ion ≤10 mmol/L, magnesium ion ≤5 mmol/L，calcium ion≤5 mmol/L，zinc ion≤50 mmol/L and copper ion≤50 mmol/L.  Conclusions　Enzymatic method meets clinical requirements with good repeatability，accuracy，stability，linearity and high anti-interference.

Key words: Sodium ion, Enzymatic method, Ion selective electrode method