The utility model belongs to the technical field of drilling tools, and relates to a percussion bit, which comprises an outer-layer percussion head, an inner-layer percussion head, an inner-layer percussion head and an outer-layer percussion head, the inner-layer
impact head is coaxially nested in the outer-layer
impact head, and a second hard
alloy tooth group is arranged on the front end surface of the inner-layer
impact head; the
slag discharging structure comprises a
slag discharging notch formed in the surface of the outer-layer impact head and a
slag discharging hole formed in the slag discharging notch so as to
discharge broken stones generated in the impact process; each of the first hard
alloy tooth group and the second hard
alloy tooth group comprises a plurality of hard alloy teeth which are annularly distributed; the first hard alloy tooth set and the second hard alloy tooth set each comprise a plurality of hard alloy teeth in the axis direction of the percussion bit, and the tooth tip of the second hard alloy tooth set does not exceed the slag discharging hole. Through cooperative guiding of the inner-layer impact head and the outer-layer impact head and real-time deslagging design,
coring-free accurate hole forming is achieved, the high-altitude
rock core falling risk is effectively eliminated, and the construction efficiency is improved.