Abstract: In this paper, an accurate RP-HPLC method for the determination of oleanolic acid 28-O-β-D-glucopyranoside (I), oleanolic acid 3-O-α-L-arabinopyranoside (II), 3β-hydroxy-oleana-11,13(18)-dien-28-oic acid (III), (ent)-pimara-8(14),15-dien-19-oic acid (IV), oleanolic acid (V) and 3-ox-oleana-12-en-28-oic acid (VI) in 11 species of Aralia Linn. was described. The analytical column used was Supelco SIL-LC-18. The mobile phase was MeOH—1%HOAc—THF (500∶110∶1, pH 3.4). The flow rate was 1.2 ml·min^-1. The detection wavelength was 205 nm. The linear ranges of I～VI were 0.135～2.160, 0.163～2.610, 0.123～1.962, 0.068～1.080, 0.135～2.160 and 0.248～2.646 μg, respectively. The recoveries of I～VI were from 86.88% to 93.31%. Detailed comparison of the diterpenoic acid, triterpenoids and tritersaponins for the group of herbal with those of woody the content of diterpenoic acid in herbal is higher than that of in woody. It showed that the diterponic acid is the specific constituent in the group of herbal, which is the difference to woody. This conclusion provides the evidence of the chemical classification for dividing the groups of herbal and woody into two distinct subgenus.