Polyaniline nanofibers/Li0.35Zn0.3Fe2.35O4 (PANI/LZFO) nanocomposite was synthesized by interfacial polymerization method. Microwave absorption mechanism for PANI nanofibers/LZFO nanocomposite is proposed. Single- and double-layer microwave absorbers were designed based on PANI nanofibers and the nanocomposite. The minimum RL value of the double-layer absorber can reach −57.5 dB with a total thickness of 2.0 mm, and the bandwidth with RL below −10 dB reaches 5.5 GHz.