In this paper, the study on pharmacokinetics of 6,7-dimethoxycoumarin in Yinchenhao Tang was reported. A reversed-phase high performance liquid chromatographic method was established for determination of 6,7-dimethoxycoumarin in rat plasma. The plasma concentrations and pharmacokinetic parameters of 6,7-dimethoxycoumarin were compared after vein administration of 6,7-dimethoxycoumarin and oral administration of 6,7-dimethoxycoumarin, Artemisiae Scopariae decoction, Artemisiae Scopariae decoction...