Abstract: Abnormal structures in coal measures strata are threatening the progress of mechanized coal mining and the safety of coal mine workers,chasms are the most common ones among them.In-seam Seismic Survey is an effective method to use the channel wave propagating in coal seam to finely investigate the abnormal structures of coal seam.To analyzing the influence of chasms on the channel wave is of great significance for prediction and location of chasms.In this paper, a three-dimensional coal-bearing strata model and a chasm model are established in comsol5.2. Using the Ricker wave with frequency of 200 Hz as the source excitation, channel wave signals carrying chasm information are obtained. The time-frequency analysis of the signals using the generalized S transform shows that the chasms will reduce the amplitude of the channel wave, resulting in the loss of partial frequency energy. When the gap of chasms is smaller than the thickness of coal , the dispersion curve will not be affected.