Five new diterpenes, trigonochinenes A-E (1-5), and two known ones, 3,4- seco-sonderianol (6) and 3,4- seco-sonderianic acid (7), were isolated from the aerial part of Trigonostemon chinensis. Compounds 1-4 possess a rare 3,4-seco-cleistanthanic skeleton, and compound 5 is a highly aromatized tetranorditerpene. Structures of these compounds were elucidated by spectroscopic analysis. The antimicrobial activities of compounds 1-7 were evaluated against a panel of bacteria and fungi.