Abstract: Rayleigh wave exploration is one of the main methods of seismic exploration in underground coal mines. However, the traditional way of dispersion curves extraction is the spectral analysis surface wave method based on the correlation of traces. This method can only extract the basic mode of Rayleigh wave. For the purpose of getting multimode dispersion curves and extending the range of exploration, we improved the F-K transform based dispersive curve generation method and applied it on actual seismic data in underground coal mine. After verification by synthetic data, we used the method in the detection of structure in working face and acquired the multimode dispersion curves. This work confirmed the existence of multimode Rayleigh wave when faults exist in coal seam.