The article tested the phenolic substances by HPLC and tartaric acid_Fe spectrophotometry, analyzed the activities of SOD, POD and PPO in female and male tree leaves of Fraxinus mandshurica. Comparation of the components and contents of the phenolic substances and the tendency of the activities of oxydases between sexes were made. The results suggested that the total amount of water soluble and methanol soluble phenolic substances in male leaves was remarkably higher than that in female during the growth season, furthermore there was significant difference in phenolic composition between different sexed leaves. The activities of SOD and POD in male and female were significant different especially in May, and the significance also exists among seasons. Determination of these differences laid both theoretical and practical foundation for further research on sapling sex identification of this tree species.
