Typical sputtering conditions based on substrate temperature, sputtering time and oxygen partial pressure to grow thin film, submicron-sized rods and trees of Cu2O on glass substrates from metallic Cu targets were investigated. The submicron-rods with diameters of 100–700 nm and lengths of 2–8 μm were synthesized. The abundance of Cu species, which is modulated by the Ar/O2 ratio during the sputtering process affects directly to the growths of the Cu2O branches on the bodies of the submicron-rods. Transmission electron microscopy and elemental mapping reveal that metallic Cu is existed on the heads of the Cu2O rods. Finally, the formation model of the submicron-sized rods and trees of Cu2O is discussed.