A method for manufacturing copper wires on a substrate for a flat panel display device is disclosed. The method comprises following steps: providing a substrate; forming a seed layer on the surface; forming a patterned photoresist on the surface of the seed layer to expose a part of the seed layer; and plating a copper layer on the exposed part of the seed layer. As the copper layer is plated, an electrolyte solution comprises a sulfur-containing compound is used. The angle between the surface of the copper layer and the contact surface of the seed layer is greater than 0 degree and less than 90 degree. Through the method illustrated above, the film step-coverage in the following process can be improved, the generated voids in device can be reduced, the manufacturing steps can be simplified, and the complicated etching process can be avoided.