The structural and magnetic properties of Co/Cu multilayers prepared by molecular beam epitaxy(MBE) and sputtering were investigated and compared with each other.It was found that the well defined layered structures existed in both samples,and the former was epitaxial single crystalline;while the latter was textured polycrystalline.Ferromagnetic resonance study showed the existence of a six-fold symmetry in the film plane,revealing the perfect in-plane structure of MBE samples.Giant magnetoresistance and its oscillation with the Cu thickness were found in sputtered samples.On the contrary,the magnetic resonance of MBE samples is smaller,about 7% for the second peak position.It is assumed that the superparamagnetic structure may be formed at interfaces in MBE samples which results in the different magnetic-field-dependent behaviors of magnetoresistance and- magnetization.