Implantable neural electrodes are important tools for interfacing with the neural system for recording and stimulation. The structural and mechanical mismatch between traditional rigid electrodes and nerve tissue can lead to an inflammatory response and signal degradation during long-term implantation. In recent years, researchers have continued to improve and innovate the material, structure, and implantation methods of electrodes to prepare flexible neural electrodes with better neural compatibility. In this review, the research progress on implantable neural electrodes is summarized from five aspects, namely materials, structures, stretchability, multifunctionality of flexible electrodes, and the application of implantable neural electrodes in nerve interfaces. Finally, the prospects for the implantable neural electrodes are discussed.