Abstract: In order to predict a seam thickness with a seismic attribute, a staggered- grid finite difference metbod was applied to establish a wedge model. The stud y results showed that when a wedge thickness was 1 14 less than the wedge seismic wavelength, the reflected wave pattern of the top interface would be steadily separ ated from the bottom interface wave pattern with the wedge thickness increased, there would be interferences from the roof and floor and there would be many time sei smic wave interferences from the interlayer within the wedge and thus this was the reason to cause the variation of the seismic amplitude attribute. There was a negativ e related relationship mainly between the amplitude attribute and the wedge thickness. When a wedge thickness was 1 14 higher than the wedge seismic wavelength, th e reflected wave pattern of the seam roof and floor interfaces would be completely separated. The seam thickness could be understood with the prediction of the seismi C amplitude attribute. The thickness of syncline axial seam in the middle of the west mining block in the mining area was thick and the thickness of the seam in west par t in the exploration region was thin relatively. The seam thickness and the amplitude envelope were negatively related and were the same to the analysis results of the wedge model.