The microwave dissipation mechanism of powder materials is different from that of bulk materials. The mixed powder of non-magnetic metal and oxide show strong absorption on microwave magnetic field. Researches which focus on the electrical conductivity and microwave magnetic absorption characteristics of the mixed powders are carried out. Samples of the mixed powders are loaded to the isolating bandpass filter which is achieved with magnetostatic surface wave, in order to study their effects on the isolation and insertion loss of non-reciprocal filter. The experimental results show that: the 30%Cu+70%CuO mixed powder sample with conductivity of 217.435 mS/m has strong absorption on the microwave magnetic field; after loading this mixed powder sample to the non-reciprocal filter, the insertion loss is reduced and the isolation is significantly increased to 21.56 dB.