Submicron diamonds were co-deposited on aluminum substrates with copper from the acid copper sulfate electrolyte by electrolyte-suspension co-deposition. After submicron diamonds were added to the electrolyte, the shape of copper grains transformed from oval or round to polyhedron, the growth mode of copper grains transformed from columnar growth to gradual change in size, and the preferred orientation of copper grains transformed from (220) to (200). Analyzing the variation of cathodic overpotential, it was found that the cathodic overpotential tended to remain unchanged when copper plane (220) grew in the process of electrodepositing pure copper, while it tended to decrease with time when copper plane (200) grew in the process of co-deposition. It was inferred that copper plane (200) was propitious to the deposition of submicron diamonds. Submicron diamonds were co-deposited on aluminum substrates with copper from the acid copper sulfate electrolyte by electrolyte-suspension co-deposition. After submicron diamonds were added to the electrolyte, the shape of copper grains transformed from oval or round to polyhedron, the growth mode of the copper grains transformed from columnar growth to gradual change in size, and the preferred orientation of copper grains transformed from (220) to (200). Analyzing the variation of cathodic overpotential, it was found that the cathodic overpotential tended to remain unchanged when copper plane was (220) grew in the process of electrodepositing pure copper, while it tended to decrease with time when copper plane (200) grew in the process of co-deposition. It was inferred that copper plane (200) was propitious to the deposition of submicron diamonds.