Abstract: The In-Seam Seismic exploration technology has high resolution,large amount of information and strong anti-interference ability.It can be used to predict the hidden small structure in the underground working face.By extracting effective information of transmission channel wave,analysing the attenuation information of the channel wave along the propagation path,using tomography to effectively reproduce the distribution of small structure.Combined with an example of underground engineering,the method of data acquisition,data processing and results interpretation of underground transmission channel wave method was introduced.The actual geological conditions verified the effectiveness of this method.