<p>The electrochemical process of Cu–Mo composite coating prepared by citric acid system was studied by electrochemical workstation, SEM, EDS and XRD. The morphology and structure of Cu–Mo composite films under different current densities (0.01, 0.015, 0.02, 0.025, 0.03 A/cm²) were analyzed. It is found that citric acid can increase the deposition potential of copper and make the deposition potential of copper and molybdenum close to each other, thus contributing to copper-induced molybdenum co-deposition. With the increase of current density, the number of particles on the surface of the deposited Cu–Mo film increases, from nanometer level to tens of microns, from dense to fluffy. And the content of Cu in the film also increases with increasing current density, while the content of Mo decreases. The characteristic peak of Cu–Mo film in X-ray spectrum shifted to the right relative to that of Cu, and a new peak appears at 44.48°, suggesting the possible formation of a new phase in the material system. In addition, by conducting electrochemical migration tests on copper substrates with and without Cu–Mo composite plating, it was found that Cu–Mo composite plating has a better inhibition effect on the electrochemical migration behavior, and it can improve the corrosion resistance of copper substrate materials.</p>