We have studied the effect of a spin-dependence interface electron scattering on the giant magnetoresistance by adding a Fe magnetic material to the Co/Cu interfaces. The $Fe(50;{AA})/[Co(17;{AA})/Fe(t;{AA})/Cu(24;{AA})]_{20}$ multilayers are deposited on the Corning glass 2948 and 7059 substrates in a dc magnetron sputtering system. The magnetoresistance ratio is 22 % in the only Co/Cu multilayer, while it is increased to 26 % with inserted ultra thin Fe interface layer and reduced with increasing thickness of the Fe interface layer. It was investigated to the dependence of the magnetoresistance behaviors on annealing temperature. The magnetic properties of the multilayers were measured by vibrating sample magnetometer. Also, the structures and the surface roughness of samples were characterized by X-ray diffraction and atomic force microscope, respectively. The magnetoresistance ratio was increased to annealing temperature $300^{circ}C$, but reduced at the temperature higher than $300^{circ}C$ due to the interfacial diffuse.