Eight new diterpenoids, leucophyllusins A-H (1-8), along with 19 known analogues (9-27) were obtained from the aerial parts of Isodon leucophyllus. Among them, abietanoids represented the predominant structural class. The structures and absolute configurations of all new compounds were unambiguously determined through a comprehensive analytical approach combining 1D/2D NMR, HRESIMS, and quantum chemical calculations. All compounds were tested for their inhibitory activity against arachidonic acid-induced platelet aggregation and lipopolysaccharide-stimulated nitric oxide production in RAW264.7 macrophage cells. However, none exhibited significant activity relative to the positive controls.