The powders of RE2Co17(RE=Y, Ce, Nd, Ho, Er) and Ho x Co100–x(x=6, 8, 10, 12) alloys were prepared by the arc melting method and high-energy ball mill process. The compositions and morphologies of the alloys were characterized by X-ray diffraction(XRD) and scanning electron microscopy(SEM), and the microwave absorbing properties were studied by a vector network analyzer. The results showed that the alloy of Y2Co17 had better absorbing properties at low frequencies and its lowest reflectivity value was –9.5 d B at 3.8 GHz. The lowest reflectivity value of Ho2Co17 alloy was –13.7 d B at 7.02 GHz and it obtained large absorbing bandwidth. Reflectivity value less than –5 d B was from 5.1 to 10.2 GHz. When x=6 and x=8, the alloys of Ho x Co100–x consisted of Ho2Co17 phase and Co phase. They had good radar absorbing properties. With increase in Ho content, the minimum reflectivity value worsened and the absorbing peak frequency shifted toward higher frequencies. But when x=12, the absorbing peak frequency shifted toward lower frequencies but the minimum reflectivity value worsened. The powders of RE2Co17 (RE = Y, Ce, Nd, Ho, Er) and Ho x Co100-x (x = 6, 8, 10, 12) alloys were prepared by the arc melting method and high-energy ball mill process. The compositions and morphologies of the alloys were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), and the microwave absorbing properties were studied by a vector network analyzer. The results showed that the alloy of Y2Co17 had better absorbing properties at low frequencies and its lowest resilience value was -9.5 d B at 3.8 GHz. The lowest possible value for the Ho2Co17 alloy was -13.7 d B at 7.02 GHz and it obtained a large absorption bandwidth. Reflectivity value less than -5 d B was from 5.1 to 10.2 GHz. When x = 6 and x = 8, the alloys of Ho x Co100-x consisted of Ho2Co17 phase and Co phase. They have good radar absorbing properties. With increase in Ho content, the minimum reflectivity value worsened and the absorption peak frequency shifted toward higher frequencies. But when x = 12, the absorbing peak frequency shifted toward lower frequencies but the minimum reflectivity value worsened.