Four new compounds: an abietane (1), two isopimarane (2 and 3) diterpenes, and a dihydrobenzofuran neolignan (5), together with a sesquiterpene glycoside (6) firstly isolated from a natural source, and a known phenol glycoside (4) were isolated from leaves of Platycladus orientalis. The structures and relative configurations of these compounds were assigned on the basis of MS, IR, 1D and 2D NMR data. The absolute configuration of compound 1 was determined via density functional theory calculations of its electronic circular dichroism. In addition, the results of bioassays indicated that compounds 4 and 6 showed a potent inhibitory effect on NO production with IC₅₀ values of 24.4 and 11.9 µM, respectively. Meanwhile, compounds 1, 2, and 3 moderately inhibited TNF- α release.