Five pentacyclic triterpenoids, oleanolic acid (1), hederagenin (2), ursolic acid (3), tormentic acid (4) and myrianthic acid (5), were isolated from the methanol extract of the leaves of Campsis grandiflora, and structures of the compounds were established by the spectroscopic methods. Compounds 2, 3, 4, and 5 were isolated for the first time from the genus Campsis. All of the compounds ($IC_{50}$: 45.3, 32.8, 82.6, 42.9 and $46.2{mu}M$ respectively) were as equivalently inhibitive as acetylsalicylic acid ($IC_{50}:57.0{mu}M$) on epinephrine induced platelet aggregation.