Abstract: The leaves of Cyclocarya paliurus from April to November in Anxi County, Fujian Province were used as the experimental materials to quantitatively analyze the mass fraction of total triterpenoids and explore the appropriate harvesting month. The results showed that the mass fraction of total triterpenoids had a very significant difference from April to November (P<0.01), and the mass fraction of total triterpenoids in June and October was higher, so June and October were the suitable harvesting months. October with the higher mass fraction of total triterpenoids was selected for the detection of terpenes in the leaves of Cyclocarya paliurus by using UPLC-MS/MS. The results showed that a total of 69 terpenoids were detected, and the triterpenoid compound accounted for the highest proportion (83.02%). Among the triterpenoid compounds, Madasiatic acid, Pomolic acid, 2α-Hydroxyursolic acid, 11-Keto-ursolic acid, α-Amyrenone, Corosolic acid, Maslinic acid, Cyclocarioside Ⅱ, and Pterocaryoside B had higher relative contents.