Abstract: In order to definite in the wounding pea seedling leaves the produced way of NO, and NO on the antioxidant system induced by injury. In this experiment pea seedlings were used to study its endogenous NO contention under wounding stress, the activity changed of NR and NOS activity, as well as the activity influenced to antioxidant enzymes SOD, POD, CAT and APX and the contention changed of H₂O₂ and O₂^-· in the leaves of pea seedlings after 24 hours by spraying processed with SNP (donor of NO), PTIO (scavenger of NO), L- NAME (inhibitors of NOS) and NaN₃ (inhibitors of NR) respectively. Results showed that NO contention in the pea seedling leaves presented a bimodal curve between 0 hour and 60 hours after the wounding treatment. The main source of NO was NOS enzymatic way when the earlier period of wounding processes (the first peak value). But the main source of NO was NR enzymatic way when the later period of wounding processes (the second peak value); during the first 24 hours, pea seedling leaf NO contention reached a highest, and the contention of H₂O₂ and O₂^-· closed to the control level, while the activity of SOD, POD, CAT and APX was higher than control significantly. When treated with SNP, it had a similar result. After the treatment with PTIO, the contention of H₂O₂ and O₂^-· increased, and the activity of SOD, POD, CAT and APX decreased. Conclusion of the research results showed that NO might reduced the membrane lipid peroxidation induced by wounding degree through enhancing the activity of protective enzyme.