Abstract: Somatic embryogenesis of Fraxinus mandshurica was conducted by using young zygotic cotyledons as explants. The polysaccharide content, soluble protein content, SOD activity, POD activity, CAT activity and PPO activity were tested for analyzing the relationships between the physiological and biochemical index and the status of somatic embryogenesis, callus induction, explants browning and growth of explants. The results showed that there was interesting correlations between the polysaccharide content, soluble protein content, SOD activity, POD activity, CAT activity and PPO activity and the regeneration of callus and somatic embryos,and explant browning and growth, and it is worth being studied further.