Abstract: A sensitive liquid chromatography-electrospray ionization-tandem mass spectrometric(LC-MS/MS) method for the simultaneous determination of TF and its metabolites M1 and M2 in human plasma were developed and validated. The plasma TF, M1, M2 were extracted using a solid phase extraction(SPE), and the sample extract was injected onto the LC-MS/MS system. The limits of quantitation(LLOQ) for TF, M1, M2 are 1 ng•L^－1. This method allowes the reproducible and accurate quantification with the concentration range of 1-500 ng•L^－1. This method can be applied to the quantitation of TF, M1, M2 in human plasma.