To completely remove oxide layer and crack layer on the inner surface of the hollow steel drill rod, deep hole reaming was processed on the inner hole of the drill rod. In view of the problems of chip discharge difficulty, high cutting temperature and poor processing quality of the inner hole surface during deep hole reaming, hydraulic low-frequency vibration assisted gun drill was adopted to improve the hole surface quality here. Experiments results showed that compared with the ordinary reaming, the hydraulic low-frequency vibration reaming can reduce the chip size and the jagged edge phenomenon on the chip surface, improve the inner hole machining surface, reduce the tool marks and scratches and the processing temperature under the condition of the speed of 500 r/min and the feed rate of 0.1 mm/r. Furthermore, Furthermore, the minimal clip size with least scratches and lowest processing temperature could be achieved when the frequency reaches 36.7 Hz with vibration amplitude at 0.58 mm. With the increase of the feed rate within the range of 0.80~0.12 mm/r, the length of chip becomes larger, and the tool marks and scratches on the surface of the inner hole increase. The speed has little effect on the chip length and the surface quality of the inner hole.