Because of the localization of light, the magneto_optical (MO) photonic crystal, composed of magnetic and dielectric films periodically or quasi_periodically, can be used to manufacture the MO isolator. A transfer matrix method, suitable for computing the propagation of polarized l ight in anisotropic media, is described in detail in this paper. Using this met hod, we discuss the MO properties of a new type of MO isolator with multi_defect , and find that the spectra are broadened with increasing number of defects. A reflection_mode MO isolator without extra reflected layers is proposed when th e number of defects is large enough.