As one kind of non-acoustic sensors,bone-conducted microphone has excellent anti-noise characteristics because its speech transmission channel naturally shields the influence of ambient noise.Recently,bone-conducted microphone has gradually played an important role in speech communication systems in various strong noise environments.However,due to the low-pass characteristic of human body and the limitations of sensor technology,bone-conducted speech sounds muffled and unclear. It is of great significance to improve the bone-conducted speech for more efficient speech communication in strong noise environments and wider application prospects of bone-conducted products.The blind enhancement algorithm means only the bone-conducted speech information can be acquired during the speech enhancement stage.This kind of direct enhancement algorithm is more applicable than the fusion technique with air-conducted speech.Here,the characteristics of bone conducted speech are firstly analyzed,then the existing methods including unsupervised bandwidth extension,equalization and spectral envelope transformation are introduced.Finally,we share some views of future research prospects.