Abstract: Based on the seedlings of Cyclocarya paliurus(1-year stem with 2 year root system), split-split plot design with three C. paliurus provenances(Wufeng, Yuanling and Muchuan)and three light conditions(full sunlight, 50% full sunlight and 15% full sunlight)was adopted to compare the content variation of total triterpenoid, arjunolic acid and cyclocarioside I in the leaves of C. paliurus seedlings under different treatments. Meanwhile, the seasonal variation of triterpenoid contents in the leaves was also discussed. The results showed that there were significant differences in triterpenoid accumulation in leaves of C. paliurus seedlings among different treatments when October is defined as leaf harvest time. The highest content of total triterpenoids(42.03 mg/g)was obtained in the treatment of Yuanling provenance with full sunlight, while the greatest contents of arjunolic acid and cyclocarioside I were achieved under the treatments of Muchuan provenance with 15% of full sunlight and Muchuan provenance with full sunlight, reaching 4.42 mg/g and 2.52 mg/g, respectively. The greatest production of total triterpenoids and cyclocarioside I was obtained in the treatment of Muchuan provenance with full sunlight, reaching 2 907.2 and 264.4 mg/plant respectively. However, the highest production of arjunolic acid was observed in the treatments of Yuanling provenance with 50% of full sunlight, hitting to 208.6 mg/plant. The accumulation of triterpenoids in the leaves of Cyclocarya paliurus are closely related to provenance, illumination intensity and the harvest time of leaves. Results from this study would provide some important practical and theoretical bases for effectively managing the plantations of C. paliurus.