It is shown by calculation that,in contrast to the usual situation of a perpendicular bias magnetic field,an inclined bias magnetic field enhances Faraday effect,and leads to modification to the properties such as the resonant frequency and the bandwidth of magnetostatic wave in magnetic waveguide.Making appropriate use of such properties,it is possible to greatly increase the magnetooptic (MO) Bragg diffraction efficiency and to improve the characteristics of guided-wave MO Bragg devices.