The invention discloses a device for automatically separating a heavy object from a parachute after air drop of the heavy object into water through the parachute. The problem that the suspended air drop heavy object and the parachute can be quickly separated after entering water is solved. In the device, a parachute connecting pin shaft (2) arranged on a U-shaped upper traction base (3) is connected with a parachute (1), a droop heavy object suspension pin shaft (25) arranged on an inversely U-shaped lower traction base (24) is in suspension connection with a droop heavy object (26), a base plate of the U-shaped upper traction base (3) is provided with a center screw hole (4), a top plate of the inversely U-shaped lower traction base (24) is provided with an inversely U-shaped lower traction base center through hole (23), an inverted wine bottle-shaped connector (7) is disposed between the U-shaped upper traction base (3) and the inversely U-shaped lower traction base (24), and a center supporting rod (5) with the vertical section in an inverse T shape is movably disposed on the upper portion of an inner cavity of the inverted wine bottle-shaped connector (7). The separation of theheavy object and the parachute is completed once the parachute enters the water, and it is ensured that the heavy object sinks to the water bottom reliably.