The invention relates to a coal seam drilling device and method capable of quickly penetrating through coal gangue. When meeting the coal gangue in a coal seam drilling process, the device can quickly change a drilling method. An original high-speed rotary drilling is converted into a drilling mode that medium-low speed rotary drilling and impact drilling are combined. Thus, the rock breaking capacity of a drilling machine is effectively improved, and the technical problem that a traditional drilling machine cannot continuously drill when meeting gangue is solved.