Taking into account the quantum size effects and considering three types of scattering from bulk impurities,rough surfaces and rough interfaces, we use the quantum-statistical Greens function approach and Kubo theory to calculate the giant magnetoresistance (GMR) in magnetic multilayered structures.Our calculations can reproduce the main features of GMR experiment, including the oscillations of GMR with nonmagnetic thickness, and the GMR increases with increasing number of bilayer N of the (Fe/Cr)N/Fe system.Moreover,whether or not additive are the parts of scattering from the impurities, surfaces and interfaces is also discussed.