Copper (Cu) pollution resulting from human activities has emerged as a prominent issue stemming from industrial development. The entry of copper into the soil, either directly or through industrial wastewater, exerts adverse effects on plant growth, leading to its accumulation in significant quantities within the plant and subsequent endangerment of human health through the food chain. DCPTA [2-(3, 4-dichlorophenoxy) triethylamine] mitigates certain abiotic stresses, yet the precise mechanism by which it alleviates Cu-induced phytotoxicity remains unknown. This study has demonstrated that DCPTA reduces the impact of copper stress on plants by enhancing leaf pigment and photosynthesis, regulating root growth, and balancing the antioxidant system. Furthermore, the accumulation of Cu in leaves and roots of cucumber treated with DCPTA was significantly lower than that in seedlings treated with Cu alone. Transcriptome analysis showed that copper absorption, transport, detoxification genes, cell wall component related genes and nitrogen metabolism related genes played a crucial role. In conclusion, exogenous application of DCPTA can partially alleviate copper stress in cucumber.