Abstract: Due to complicated underground environment, traditional active location technologies make it inconvenient for workers to carry tags or lose tags during operation, which are limited in application of underground target location, while existing passive location technologies such as geometric method, fingerprinting method and so on has low location precision due to dense multipath interference in underground, which cannot be used in underground directly. For the above problems, a mine tagless target location method based on combined space and frequency diversity is proposed. The method, which is based on non-uniform sampling principle in Fourier domain, reconstructs target reflectivity function through inverse Fourier transform of echo signals of the target in wavenumber domain, so as to realize target location. Passive broadband harmonic tags are used to generate the required harmonic signals for eliminating fundamental frequency interference introduced by transmitting antenna. The combination of space and frequency diversity is achieved by using space diversity of the tags and frequency diversity of the harmonic signals and fusing multi-channel information, which solves the problem of low location precision caused by insufficient sampling information. A differential reception algorithm is used to eliminate phase errors caused by downlink multipath interference, which can improve mine tagless target location precision. The simulated experiment results show that the method can effectively expand coverage of wavenumber domain and restrain multipath interference, so as to realize accurate target location. Under the condition of low signal-to-noise ratio, the location precision can reach decimeter level.