Abstract: To elucidate the effect of nitrogen on biomass of shoot, protective enzyme activities and lipid peroxidation in triticale leaves at different growing stages (seeding, tillering, jointing and heading), a pot experiment was carried out using four N levels (0, 0.25, 0.50 and 1.00 g N/pot) with two triticale genotypes, one of high N use efficiency (P1429186) and one of low N use efficiency (Clxt74). 1) At the same N levels, shoot biomass of P1429186 was significantly greater than that of Clxt74 at different growth stages. At the same growth stages, shoot biomass was greater when more N was supplied, and the increasing capacity of P1429186 was much greater than that of Clxt74. 2) During seeding, the activities of superxoide dismutase (SOD), peroxidase (POD), and catalase (CAT) in leaves of P1429186 were greater than in Clxt74 at the same N levels. Contrarily, malondialdehyde (MDA) content was significantly lower in P1429186 than in Clxt74. 3) Correlation analysis showed that shoot biomass had various correlations with the activities of SOD, POD, and CAT in leaves of triticale at different growth stages, and had a negative correlation with MDA content. This indicated that, the protective enzymes of P1429186 can cooperate with each other to eliminate reactive oxygen species, thereby inhibiting membrane lipid peroxidation to increase photosynthesis and yield.