The Sr-W type planar hexagonal ferrite was synthesized by a sol-gel method, and its morphology and phase structure were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The microwave absorbing properties of the mixtures with different ratios of Ni/ferrite were studied by vector network analyzer (VAZ). The results demonstrate that with the increase of hexagonal ferrite content, the microwave absorbing peaks of the mixtures shift to higher frequencies, and when the mixture consists of 20% Ni and 80% Sr-W-type ferrite, its microwave absorbing performance is the most advantageous. When absorbing coating thickness is 2 mm, the minimum reflectivity and absorbing peak frequency is –20.69 dB at 12.08 GHz and the bandwidth less than –10 dB reaches 4 GHz. The absorbing peak shifts to low-frequency with the increase of absorbing coating thickness, and when the coating thickness reaches a certain value, the two absorbing peaks appear in the mixture in the frequency range of 2~18 GHz, which is of significance to explore the absorbing material with bandwidth effect.