Objective To analyze the correlation of valproic acid and its metabolites (2-propyl-4-pentenoic acid, 3-hydroxy valproic acid,5-hydroxy valproic acid) with liver injury reference index. Methods 328 plasma samples from epilepsy patients were collected and divided into two groups（123 samples from patients with abnormal liver function, experimental group; 205 samples from patients with normal liver function, control group）.The plasma concentrations of valproic acid and its metabolites in the two groups were determined by LC-MS/MS method and the diagnostic value of the concentrations to liver disfunction was analyzed by ROC curve. Results The mean plasma concentration of valproic acid and its three metabolites in the patients with abnormal liver function was higher than that in the control group with was statistically difference（P<0.05）.The concentration of valproic acid and its metabolites could be used as a reference for the diagnosis of liver injury,5-hydroxy valproic acid had better diagnostic value than valproic acid. Conclusion The metabolites of valproic acid were associated with hepatotoxicity, which could be used as a diagnostic index of liver injury and could be a reference for clinical safe application of valproic acid.