Abstract: The concealed fault influences not only the highly efficient extraction of coal resources, but also brings potential threat for safe production in coal mine. The paper conducted in-seam seismic numeric simulation for the concealed fault in a working face, verified the feasibility of the detection of the consealed fault by transmission method. Then the holographic observation was used to conduct transmission in-seam wave detection in working face 45301, through analysis of frequence dispersion and CT imaging, the distribution of the conceraled faults in working face was found out. The comparison of the detection and the mining show that the transmission in-seam detection tehnique can efficiently detect the consealed faults in working face, provide efficient technical support for safe mining in coal mine.