The dynamics of flavonoids content during the growing period of Cyclocarya paliurus leaves from five provenances was studied to determine the optimum harvesting time of leaves and to select superior provenances. The content of flavonoids in the leaves was determined with HPLC and the data analyzed by SPSS software. Results indicated that there were significant differences in flavonoids content of leaves among different harvesting months for each provenance. The best harvesting time was in July for Jianghua and Lushan provenances, and in October for the other provenances. Significant differences in the average flavonoids content of leaves were also observed among different provenances, and the Jianghua and Lushan provenances were considered elite ones for medicine use in light of flavonoids content. The obvious differences mentioned above made it necessary to choose the best utilization time and to select superior provenances in order to make full use of C. paliurus leaves.