Based on the phenomenological theory in which the mixed layer composed of the ferro magnetic and nonmagnetic materials is introduced in lieu of the interface, we calculate the dependences of the giant magnetoresistance (GMR) in Fe/Cr multilayers on the thicknesses of ferromagnetic (FM) layers and non-magnetic (NM) layers. Good agreement of the calculated resutls with experimental ones is found. The two-variable function of the GMR respect to the thicknesses of FM and NM is plotted.