The objective of this study is to quantify the puerarin in rat plasma following oral administration of TZ18 and compare the pharmacokinetics characteristics of puerarin in normal rats with that in depression model rats. A high performance liquid chromatography method was used to quantify the puerarin due to its Intra- and inter-day precision coefficients of variation and accuracy bias were acceptable (Maximum coefficient of variation was 5.74% for intra-day and 3.09% for inter-day) over the entire range. The recoveries spectively. The concentration-time curves for both normal rats and depression model rats were fit to a twocompartment model with the first order absorption. The results show significant differences in the main pharmacokinetic parameters of peak time, peak concentration, and the area under the concentration-time curve between the two kinds of rats.