A one-dimensional photonic crystal structure including two nonsymmetric magneto-optical (MO) metal defects is proposed to achieve nonreciprocal transmission. The nonsymmetric magnetic microcavities are made of the MO metal defects in photonic crystal. The transmission properties of the structure are studied by the transfer matrix method based on the MO material. The MO effect breaks the time-reversal symmetry while the coupling of two nonsymmetric microcavities breaks the mirror symmetry, which results in nonreciprocal transmission. With the increase of incident angle, the interval of two nonreciprocal tunneling channels increases and reaches its maximum at 50°. When the external magnetic field increases, the interval of two nonreciprocal tunneling channels increases and reaches a maximum at a certain value. The results are demonstrated through an electromagnetic field simulation based on the finite element solver.