Cysteine (Cys) is one of the twenty basic amino acids and is converted to glutathione (GSH), phytochelatins (PCs) and other variety of metabolites in the body. GSH is an enzymatically synthesized tripeptide in which Cys is linked via peptide bonds to the γ-carboxyl group of glutamic acid (Glu) and the α-amino group of glycine (Gly) depending on peptide bonds. GSH serves as the first line of the organism defense against the products of oxygen metabolism, reactive oxygen species, and other electrophilic compounds such as toxins (herbicides), xenobiotics, and heavy metals. PCs are a family of heavy metal-inducible peptides important in the detoxification of heavy metals and can chelate the metals, have been identified in plants and some microorganisms. The inactive toxic metal ions of metal-PCs chelatins are subsequently transported from cytosol to vacuole before they poison the enzymes of life-supporting metabolic routes, and transiently store in vacuole to reduce the heavy metal concentration in cytosol. Thus, heavy metal detoxification is attained. When one considers that Cys plays a central role, it is perhaps understandable that the effects of exogenous Cys have been less well studied in higher plants. In this paper, the effects of exogenous Cys on growth, copper accumulation and antioxidative systems in wheat seedlings under 200μmol/L copper stress culture method. The results showed that the growth of wheat seedlings were inhibited under 200 μmol/L copper stress, and that the radical elongation, biomass and total chlorophyll content decreased highly significantly, the contents of soluble protein and GSH, the activities of superoxidase dismutase (SOD) and ascorbate peroxidase (APX) increased slightly. Malondialdehyde (MDA) content and the membrane permeability enhanced significantly. At 1.0-5.0mmol/L exogenous Cys level, the seedling growth was similar to that of the control ones, and at 1.0 and 2.5mmol/L exogenous Cys level, the radical elongation, biomass, chlorophyll a and total chlorophyll content were no significantly different compared with those of the control ones, while significantly different from those with Cu treatments (P<0.01). Above 1.0mmol/L exogenous Cys level, copper accumulation increased continuously in wheat leaves and roots. Exogenous Cys significantly enhanced the contents of soluble protein and GSH, and maintained the activities of SOD and APX at a low level continuously. In contrast, MDA content decreased significantly at the level of less than 2.5mmol/L Cys, while the membrane permeability increased significantly. Polyphenol oxidase (PPO) activity increased firstly and then decreased, showing no significant differences from control ones except with 0.5mmol/L treatment. On the whole, spraying 1.0-2.5mmol/L exogenous Cys can enhance the tolerance of wheat seedlings to copper.