Copper is very important to plant growth, but excessive copper in soil not only affects the yield and quality of crops, but also threatens the health of animals and humans through the food chain. Therefore, it is important for agricultural production to find effective ways to alleviate the inhibition of copper stress on plant growth and reduce copper content in plants. In this study, pot experiments were conducted to investigate the effects of different concentrations of chitooligosaccharide on Rumex growth, antioxidant system and copper enrichment and transport under copper stress, providing a new strategy for crop cultivation in copper-contaminated soil. The results showed that exogenous chitooligosaccharide significantly increased chlorophyll content and antioxidant enzymes activities of SOD,POD and CAT under copper stress, and reduced the accumulation and transport coefficients of copper, thus improving the tolerance of Rumex to copper stress and reducing copper content in stems and leaves. The application concentration of chitooligosaccharide should be controlled at a reasonable level, and the concentration of 50～100 mg/L is more suitable.