Abstract: The research on passive fiber switch is attracting the people's attention in the optical communication. In this paper a new Magneto-optical crystal material used in the fiber switch has been researched theoretically and experimentally.It is decided that the fiber switch made of the material can work in the wavelength rang of 0.5～1.5μm, the excitation pulse current for the switch is lower than 4A and the pulse duration is about 5μs.