Abstract: In order to adapt the need of mine construction for the coal seam thickness detection by seismic exploration in mining area,and proceed from the characteristic of coal seam as a "thin layer" in seismic exploration,the mathematical expression of coal seam reflected wave is established,and directly inversed in the frequency domain.The coal seam thickness is detected by the spectral square ratio method which can reduces the effects of non-thickness factors,the good effectiveness is obtained,and the requirement of mine construction can been achieved.