Speech signal acquisition is of great significance for human communication. Bio-radar technology has many advantages, such as it is noncontact, noninvasive, safe, highly directional, highly sensitivity, immune to strong acoustical disturbance and penetrable. This technology has important applications in the field of speech detection. In this paper, we first review the developmental history of speech detection technology, and then summarize the status of bio-radar speech detection technology. The basic principles of a bio-radar in detecting speech signals are given, and the performance of three types of bio-radar speech detection systems are compared in this paper. Finally, the potential applications of bio-radar speech signal detection technology are prospected.