The present disclosure belongs to the field of machining of chamfers of holes. The hole chamfering device includes blades in bilateral symmetry and a blade distance adjusting, through the blade distance adjusting, the distance between the blades on the left side and the right side can be adjusted, thus, after the blades on the left side and the right side of the hole chamfering device process chamfers on the front face of a hole, the distance between the blades is reduced to enable the blades to pass through the hole to process chamfers on the back face of the hole, after processing of the chamfers on the back face of the hole is completed, the distance between the blades is reduced, the hole chamfering device not only can chamfer the front face of the hole, but also can chamfer the back face of the hole.