A hydroponic experiment was conducted to study the effects of different glycine（Gly）concentrations on bakchoi〔Brassica campestirs L. spp. chinensis（L.）Makino var. communis Tsen et Lee〕seedling growth and nitrogen metabolism．The differences of dry matter，total N content，total carbon content and key enzyme activities involved in nitrogen metabolism in 2 pakchoi cultivars（‘Huawang’and‘Wuyueman’）and under 4 Gly concentration（0，2.5，5.0，10.0，20.0 mmol·L^-1）were compared．The results indicated that the dry matter，total N content，total carbon content and key enzyme activities involved in nitrogen metabolism first increased then decreased with the increase of Gly concentration．Under 2.5-10.0 mmol·L^-1 Gly treatment，the dry matters，total N contents，total carbon contents，the activities of glutamine synthetase and glutamate synthase，and root nitrate reductase，root glutamic-pyruvate transaminase，root glutamic oxalo-acetic transaminase of the 2 pakchoi cultivars were generally significantly higher than that of the contrast．Under 20.0 mmol·L^-1 Gly treatment，the dry matters，total contents of N and C and the activities of most enzymes for both cultivars showed no significant difference with those in the contrast，while the dry matter，total N and C content of‘Wuyueman’were lower than that of the contrast．These results clearly demonstrates that suitable Gly concentration can promote the accumulation of N and C and promote pakchoi growth with relatively greater activities of nitrate reductase，glutamicpyruvate transaminase，glutamic oxalo-acetic transaminase in roots and GS-GOGAT cycle in both shoots and roots．