In the process of design RF cavity of CSRe, we use ferrite as the loading material of cavity. The characteristic of ferrite directly affects whether the cavity can obtain the target designed, so the measurement of ferrite material appears most important obviously.The complex permeability is In the process of design RF cavity of CSRe, we use ferrite as the loading material of cavity. The characteristic of ferrite directly affects whether the cavity can obtain the target designed, so the measurement of ferrite material appears most important obviously. The complex permeability is