Abstract: The diterpene quinone components in lipid soluble fractions of Danshen were studied by HPLC-ESI/TOFMS. The lipid solubles were extracted with a mixture of chloroform and methanol (1∶4, V/V). The extract was dried by a gentle stream of nitrogen， and the residue was diluted in methanol for analysis. HPLC was performed on a reversed-phase C₁₈ column using isocratic elution with a mixture of methanol and water with the addition of 0.1% acetic acid and 5 mmol•L^-1 ammonium acetate. Accurate molecular weights of individual tanshinones were determined through ESI-TOF/MS on-line detection. The molecular formula and TOFMS fragmentation behavior of each compound were obtained through off-line analysis under different collision induced dissociation (CID) energies. Combining literature information with the observed data, 16 tanshinones in lipid-soluble fractions of Danshen were tentatively identified in a run. The method demonstrates high potential as a rapid and effective method for the preliminary structural screening and speciation of bioactive tanshinone components in Danshen or other herbal extracts.