The invention relates to a barrel brushing machine for brushing the inner wall and outer wall of a drinking water barrel. The barrel brushing machine comprises a rack, a barrel feeding mechanism, a turning-over mechanism, an inner hair brush mechanism, a barrel bottom hair brush mechanism, a first outer hair brush mechanism, a second outer hair brush mechanism and a barrel discharging mechanism. The barrel feeding mechanism is arranged on one side of the rack; the turning-over mechanism is arranged on one side of the barrel feeding mechanism; the inner hair brush mechanism is arranged in the turning-over mechanism; the barrel bottom hair brush mechanism is arranged above the turning-over mechanism and is opposite to the inner hair brush mechanism; the first outer hair brush mechanism is arranged on one side of the barrel bottom hair brush mechanism and is close to the barrel feeding mechanism; the second outer hair brush mechanism is arranged on the other side of the barrel bottom hair brush mechanism and is opposite to the first outer hair brush mechanism; the barrel discharging mechanism is arranged on the other side of the rack, opposite to the barrel feeding mechanism and is close to the second outer hair brush mechanism. The barrel feeding mechanism and the barrel discharging mechanism of the barrel brushing machine are arranged separately, in this way, barrel feeding, barrel brushing and barrel discharging can be performed at the same time without mutual interference and disturbance, brushing efficiency of the barrel brushing machine is improved, and the yield is raised.