Abstract: In this paper, the effects of the addition of Cu element on the microstructure, mechanical properties and corrosion resistance of a high-Mn cryogenic steel were investigated with the use of metallographic, transmission electron microscope (TEM), tensile, Charpy impact and electrochemical corrosion tests. The purpose of this paper is to systematically explore the effect laws and mechanisms of Cu addition on the microstructure and properties of high-Mn cryogenic steel and to establish a quantitative correlation between composition, microstructure and properties, which can provide theoretical support for the development of a new generation of high-Mn cryogenic steel with high strength, good toughness and excellent corrosion resistance. It is observed that the addition of Cu element leads to a significant increase in the yield strength of the experimental steel and the related strengthening mechanism is solution strengthening. The deformation twinning is found to be suppressed due to the addition of Cu element, which results in the decrease in the total elongation and impact toughness of the experimental steel. A protective oxide film can be formed on the surface of the experimental steel by Cu element, contributing to the improvement in the corrosion resistance of the experimental steel. The high-Mn cryogenic steel with more excellent comprehensive properties can be obtained by the addition of 0.5% mass fraction of Cu element.