Abstract:A new chlorinated diterpene epoxide, dichlorotriptetraolide (L5) was isolated from the leaves of Tripterygium wilfordii Hook. f. Dichlorotriptetraolide was crystallized from CH3OH as colorless needle-like crystal, with amp of 252.0～253.5 ℃. Its molecular formula is C2oH26O7Cl2. The structure was identified on the basis of spectral analyses (UV, 1H-NMR, 13C-NMR. 13C-NOE. 2D-cosy. LD/FTMS. EIMS, selective long-range DEPT spectrum and X-ray fluorescence spectrum) and computerization of molecular mechanics and molecular graph.