Within the framework of effective-mass approximation, the properties of the localized electronic states in a N-layer superlattice (SL) with structural defects in finite magnetic fields are investigated by utilizing the transfer matrix and effective barrier-height methods. When the mismatch of electron effective mass in different constituent layers is considered, an external magnetic field will lead to the magneto-coupling. The numerical results show that the magneto-coupling brings about not only quantization of localized electron levels but also the degree of the strong dependence of the localized levels on Landau indices and magnetic fields, especially for the localized levels in higher energy region. In addition, we demonstrate in detail the correlations between the localized electronic states inside the minigaps of the infinite SL with structural defect layer and the resonant transmission peaks in dips of the finite SL. A good coincidence between the localized states and transmission peaks is found, which provides a theoretical basis for experimental observation of the localized electronic states in SLs.