A pot experiment was conducted to investigate effects of cadmium stress on nitrogen metabolism and photosynthesis of low nitrate accumulator and high accumulator of Chinese cabbages (Brassica campestris L.ssp.) Cd was applied with five levels of 0,0.5,1.0,5.0 and 7.0 mg/kg soil.The fresh weight,concentrations of nitrogen,ammonium,free amino acid,and soluble protein,activities of nitrate reductase (NR),glutamine synthetase (GS) of leaves,net photosynthetic rate (Pn),stomatal conductance (Gs),intercellular CO2 (Ci) and transpiration rate (Tr) were determined.The results showed that the fresh weight of the low nitrate accumulator decreased significantly with the increase of Cd concentration.The concentrations of nitrogen and soluble protein in the leaves of the low nitrate accumulator decreased with the increase of Cd concentration.Accumulations of ammonium and free amino acid in the leaves of both Chinese cabbage cultivars were detected under the Cd stress,especially in the low nitrate accumulator.Cadmium induced a significant inhibition on the activities of nitrate reductase(NR) in both cultivars.Under the Cd stress,activities of nitrate reductase (NR) and glutamine synthetase (GS) in leaves of the low accumulator were lower than those in leaves of the high accumulator.Treated with both 0.5 mg/kg and 1.0 mg/kg,net photosynthetic rate (Pn),stomatal conductance (Gs),intercellular CO2 (Ci) and transpiration rate (Tr) of both Chinese cabbage cultivars increased.Treated with high Cd concentrations (5.0 mg/kg and 7.0 mg/kg) these parameters were decreased.It is indicated that cadmium disturbed nitrogen metablism and decreased net photosynthetic rates of both Chinese cabbage cultivars.All indexes of changes for the low nitrate accumulator were greater than that for the high nitrate accumulator.