The utility model relates to a drilling device which is used for drilling drill holes filled with brush bristles out of a brush body. The drilling device comprises a drill bit maintaining portion and a brush body maintaining portion, wherein the drill bit maintaining portion can be driven by a driving motor in a rotary mode and bear a drill bit, and the brush body maintaining portion can move in the longitudinal direction and the transverse direction of the brush body while the brush body is positioned by the drill bit. The drill bit maintaining portion can move in an angular mode relative to the brush body, can bear a shaft in a rotary mode and is in driving connection with the shaft, a gear or a belt pulley is arranged on the shaft in a longitudinal sliding mode instead of a relative rotation mode, the shaft is structurally a roll ball spline shaft, the gear or the belt pulley is arranged on the roll ball spline shaft through a roll ball spline in a sleeving mode and can be guided in a longitudinal sliding mode instead of a relative rotation mode, and the gear or the belt pulley is in driving connection with the driving motor through a corresponding gear or a transmission belt. The drilling device has the advantages of being long in service life and maintenance interval, relatively high in machining speed and simple to maintain.