Abstract: In order to explore the effect of different bottom coal thickness on roadway floor burst induced by dynamic disturbance, dynamic response laws of roadway floor burst of special thick coal seam induced by stress wave at different bottom coal thickness were studied by using rock mechanics and FLAC^2D finite difference numerical software. The results showed that the role of dynamic disturbance was to increase coal stress, break the balance condition and induce floor burst under ultimate stress. The floor instability would not be caused as and the floor instability would be caused easily and strength of floor burst increased slowly as under dynamic loads if bottom coal below was formed by the thick and hard coarse sandstone. The risk of secondary floor burst would decrease after first floor burst.