Abstract: In vitro cultivar of Paeonia suffruticosa‘Taipinghong’was used to study histological characters and the contents of IAA，ZR and ABA and the activities of POD，PPO and IAAO during rhizogenesis. Results identified that the adventitious root primordia originated from the vascular cambium cells. The adventitious root primordia formed on the 3rd day of root induction period and broke epidermis on the 15th day. The contents of endogenous hormones decreased during root primordia-inducing but increased during root elongation. Moreover，the activity of POD fell but the activity of PPO and IAAO rosed during root primordia-growing；And the activity of POD fluctuated，the activity of PPO decreased then increased，the activity of IAAO decreased during root elongation.

Key words: Paeonia suffruticosa, in vitro shoot, endogenous hormone, enzyme activity, anatomical structure