(1) Pseudolaric acids--Novel diterpenes, Pseudolaric acid A, B, C and D were isolated from Pseudolarix kaempferi Gorden (pinaceae). Their structures were assigned by spectroscopic data and chemical correlations. In the continuous studies, the absolute configurations, the conformations in the solutions, the fragmentation mechanisms of MS and assignments of all NMR spectral signals were also reported. They showed the antifungal and cytotoxic activities. (2)--Daphnane diterpenes--In the further studies on the plants of Thymelaeaceae, besides 10 known diterpenes, 16 new daphnane diterpenes were isolated from Daphne genkwa, D. tangutica, D. giraldii, Wikstroemie chamaedaphne. They showed the antifertilities activities. (3) Tripterygium diterpenes--14 new diterpenes were isolated from Triperygium wilfordii, T. regeli and T. hypoglaucum. Some of them showed the antitumour activities. The CD spectra showed that A/B ring of all compounds have trans configuration as same as tripdiolide and triptolide determined by X-ray diffraction. (4) Pregnane glycosides from Marsdenia koi--Two new pregnane glycosides marsdenikoiside A and marddenikoiside B which can terminate the early pregnancy were isolated from Marsdeia koi. Their structures were elucidated by hydrolysis and spectroscopic methods.