To explore the effects of nutrients on the performance of plants in response to copper (Cu) stress, we conducted a three-week hydroponic experiment with barley (Hordeum vulgare) seedlings, using two nutrient levels (10% and 35% Hoagland solutions) and three Cu stress levels (0, 1 and 10 mg(L^-1). The results showed that 35% Hoagland solution, compared to 10% Hoagland solution, generally increased the biomass, leaf relative chlorophyll content (RCC) and activities of antioxidant enzymes of barley seedlings under Cu stress. However, the degrees of these alleviation effects varied with the levels of Cu stress. Under the level of 1 mg(L^-1 Cu stress, more nutrient supply, in terms of the use of 35% as compared to 10% Hoagland solution, significantly increased plant biomass, RCC and the activity of superoxide dismutase (SOD); while under the level of 10 mg(L^-1 Cu stress, more nutrient supply also significantly increased the activities of peroxidase (POD) and glutathione peroxidases (GPX) but had no effect on RCC. In addition, the inhibition effects of Cu stress were stronger on root growth than on aboveground growth. Under 10% Hoagland solution condition, the level of 1 mg(L^-1 Cu stress significantly increased RCC as compared to that in the control treatment. These results suggested that increasing nutrient supply can enhance the growth tolerance of barley to Cu stress.