This research experimentally investigated how the solid fraction level of an array of projecting nickel cylindrical microstructures influenced the electrodeposition of Cu-Ni alloy on the cylindrical microstructures. The electrodeposition of Cu-Ni alloy on a substrate with an array of projecting cylindrical structures resulted in the concentrated precipitation of Cu ions at the top of the cylinders. Relatively more electrodeposited structures were formed at the top surface of the cylinders than at the bottom surface, and electrodeposited structures were not formed at the bottom surface of the substrate when the solid fraction was increased. Structures at the edges of the cylinders' top surfaces grew larger than the structures at the centers of the surfaces. The heights of the electrodeposited structures decreased as the solid fraction increased. In addition, shadow bands with no electrodeposited structures were observed at the bottom surface of the substrate a certain distance away from the cylinders.