Abstract: The small collapse columns in working faces of a mine in Shanxi are relatively developed and dense, easy to be missed in detection before mining, inhibiting the normal extraction of the working faces and bringing potential threat to the safe production of the mine. The transmitted in-seam wave method with high number of ray coverage and multi-directional ray observation was used in detection, and interpretation was carried out by using CT imaging technology. The results show that the transmitted in-seam wave can accurately detect the boundary and location of the collapse column in the working faces.