The utility model discloses an automatic winding mechanism for an earth bin, which comprises a body, two linear guide rails are vertically arranged at opposite positions in the body, a bed frame capable of moving up and down is arranged on the linear guide rails, and a guide sleeve matched with the linear guide rails is arranged on one side of the bed frame; a motor is arranged at the bottom of the body, a lead screw is arranged on an output shaft of the motor, a matched lead screw nut is arranged on the lead screw, and the lead screw nut is connected with the guide sleeve through a horizontally-arranged transmission plate. A rotatable rotating shaft is horizontally arranged at the bottom of the bed frame, volute spiral springs are arranged at the two ends of the rotating shaft respectively, and two bed legs are arranged at the opposite positions of a rotating shaft rod. A rod sleeve is vertically arranged on the side face of the bed frame, an ejector rod capable of vertically moving is arranged in the rod sleeve, and the upper end of the ejector rod is connected with the protruding portion of the eccentric block through a traction rope. A limiting plate is arranged below an ejector rod at the bottom of the linear guide. The utility model aims to provide the automatic winding mechanism for the earth bin, the bed frame descends to realize automatic extension and automatic winding of the bed legs, and the automatic winding mechanism is simple to install and adjust.