Camptotheca acuminata Decne. (Nyssaceae) is a major source of anticancer camptothecin (CPT). It is imperative to induce CPT accumulation in order to develop CPT production strategies to satisfy clinical uses of CPT. In this study, twoyearold C. acuminata were dealt 8 h each day with UVB radiation for 12 days, and oneyearold C. acuminata were respectively arranged to radiate 2 h，4 h，6 h and 8 h with UVB radiation each day for 12 days. The contents of chlorophyll, MDA and free proline (Fpro), the activity of SOD in leaf and CPT content in young leaves, young shoots and root were separately measured after UVB treatment. In order to reveal that camptothecin is the defense product of UVB stress, the effects of UVB radiation on the physiological indices and secondary metabolites were analyzed. The results showed that: (1) in twoyearold C. acuminata, chlorophyll content was significantly decreased, MDA, Fpro and CPT contents were significantly increased after 8 h UVB treatment daily. It indicated that 8 h UVB radiation caused great stress influences on twoyearold C. acuminata. (2) In oneyearold C. acuminata, with the time of UVB radiation increasing, chlorophyll content was gradually decreased; Fpro content was significantly increased; MDA content had no significantly difference between 2 h and 6 h UVB radiation, but significantly increased after 8 h radiation compared with the control; SOD activity decreased firstly, then increased, lastly decreased with the time of UVB radiation prolonging every day. It showed that 8 h UVB radiation also caused stress influences on oneyearold C. acuminata. (3) CPT contents in vegetative organs of oneyearold C. acuminata were gradually increased with the time of UVB radiation prolonging, and the contents were the highest after 8 h UVB radiation each day. Moreover, CPT content increased more obviously in young leaves and young shoots than those in roots. It confirmed that enhanced UVB radiation caused certain damage to C. acuminata, and C. acuminata responded to this stress by not only changing physiological indices, but also changing secondary metabolism to accumulate CPT.