The invention discloses a detachable device and usage thereof. The detachable device comprises a connecting belt piece A (1), a detachable fastener (2) and a detachable rope (3), wherein the middle of the detachable fastener (2) is provided with a hole (5) penetrating through the detachable fastener (2), the top of the detachable fastener (2) is provided with a slot (6) communicated with the hole (5), and the bottom of the detachable fastener (2) is connected with a fixed point. The starting end of the connecting belt piece A (1) is provided with a passage (7) which is inserted into the hole (5) through the slot (6), the starting end of the detachable rope (3) is inserted into one end of the hole (5) of the detachable fastener (2) and penetrates out of the other end of the hole (5) through the passage (7), the width of the slot (6) is not larger than the diameter of the detachable rope (3), and the length of the slot (6) is not larger than the width of the connecting belt piece A (1). The detachable device can be assembled at connecting positions requiring quick detachment.