The invention discloses an automatic lifting hook pay-off device for a crane. The crane comprises an arm frame installation base and a basic lazy arm hinged to the arm frame installation base. The basic lazy arm is internally provided with at least one extensible and retractable lazy arm and a supporting sliding wheel which is arranged on the basic lazy arm and is in rolling connection with the extensible and retractable lazy arm. The extensible and retractable lazy arm farthest to the basic lazy arm is provided with a lifting hook assembly. The arm frame installation base is provided with a rotary winch. The winch is connected with a lifting hook of the lifting hook assembly through a steel wire rope. The steel wire rope is wound around the supporting sliding wheel. The automatic liftinghook pay-off device comprises a first detection piece, a second detection piece and a control unit, wherein the first detection piece is arranged on the winch and used for detecting the number of rotating turns of the winch, the second detection piece is arranged on the side portion of the basic lazy arm and used for detecting the number of rotating turns of the supporting sliding wheel, and the control unit is electrically connected with the first detection piece and the second detection piece. The automatic lifting hook pay-off device has the effects that the working efficiency is high, thelabor intensity is low and potential safety hazards caused by twisting of the steel wire rope are avoided.