The present disclosure provides a device for fixing a gantry crane rail in a factory building and a gantry crane system using the same. The device comprises a main body, which comprises a top portion, a first surface and a second surface opposite the first surface. The top portion is fixed to a bottom surface of a beam of the factory building, and the first surface and the second surface are substantially parallel to the crane rail. The device further comprises a first protruded support positioned on the first surface and a second protruded support positioned on the second surface.