We present a two-dimensional magneto-optical photonic crystal waveguide, in which TM mode with proper frequency can propagate only in one direction. The photonic crystal is composed of square-lattice yttrium-iron-garnet (YIG) rods, with static magnetic field applied on it. In a special frequency range, this waveguide possesses only forward mode, while in another special frequency range, only backward mode. We also study the coupling of electromagnetic wave into it from air as well as from conductor waveguides. Numerical results show that the magneto-optical PhCs (MPC) waveguides have special transmitting performance, and can show high efficiency when electromagnetic wave is coupled into this waveguide.