The utility model relates to a gantry crane rail transfer device for a heavy haul railway beam yard. Horizontal rails and longitudinal rails are perpendicularly intersected, gaps with same length are arranged at the intersected parts, the transfer device is of a transfer rail and is slightly shorter than each gap, the transfer rails are interchanged and connected between the horizontal rails and the longitudinal rails, and reinforced plates are arranged at two sides of the lower part of the transfer rail. The gantry crane rail transfer device is simple to manufacture and convenient to use, saves the transfer time of the rails, improves the working efficiency and is low in invest cost and high in safety.