Automatic hoisting system and method for gantry crane

The invention provides an automatic hoisting system and method for a gantry crane. The automatic hoisting system for the gantry crane comprises a cart mechanism, a trolley mechanism, a hoisting mechanism and a plate turnover mechanism. The cart mechanism moves along the direction of the construction track; the trolley mechanism moves in the length direction of the beam. The lifting mechanism drives the lifting appliance to move in the vertical direction; the plate turnover mechanism is cooperated with the hoisting mechanism to turn over the muck box; a control system of the cart mechanism, a control system of the trolley mechanism and a control system of the hoisting mechanism are all in communication connection with a PLC, absolute value encoders are further arranged in the cart mechanism, the trolley mechanism and the hoisting mechanism and are configured to obtain three-dimensional position information of the lifting appliance, and the PLC is configured to automatically control movement of the cart mechani