As an indispensable trace element in the body, copper is a cofactor on the active sites of a variety of enzymes and participates in energy metabolism, anti⁃oxidation, blood coagulation, neurotransmitter synthesis, iron metabolism, pigmentation and other important life activities. Abnormal copper metabolism can cause serious diseases, such as Menkes disease caused by copper deficiency and hepatolenticular degeneration caused by excessive copper accumulation. The importance and potential toxicity of copper determine that its transportation and distribution in the human body need to be regulated by a complex and sophisticated transport system, which involves a variety of copper chaperones and transport proteins. Therefore, copper is inseparable from its related proteins. The copper level in tumor tissues and serum of patients with cancer is significantly elevated. In recent years, studies on the molecular mechanisms of copper ions and copper⁃related proteins regulating tumor proliferation have become more and more in⁃depth. It is now clear that copper ions and copper⁃related proteins are involved in the occurrence and development of tumors, especially in the activation of signal pathways related to tumor cell invasion and metastasis. In addition, there is crosstalk between copper ion and tumor micro⁃environment, which can jointly regulate tumor proliferation and metastasis. This review will discuss the physiological metabolic pathways of copper in the human body, the effects of copper ions and copper⁃related proteins on the tumor tissue and tumor micro⁃environment, and introduce new therapies that target copper ions and copper⁃related proteins, which could provide new ideas for tumor research, diagnosis and treatment, and provides a strong theoretical basis for the application of copper chelators in tumor treatment.