JMG rail type container gantry crane is composed of main girder, rigid and flexible gantry legs, running trolley, lifting mechanism, truck operating mechanism, electrical system, operating cab and so on. According to the operation process of the yard, the overhanging cantilever in the direction of single leg or double leg becomes a single cantilever or double cantilever model, and the non-overhanging becomes a non-cantilever model. According to the site, container storage and transportation process and the loading and unloading vehicles (container trucks or railway vehicles) to determine the use of non-cantilever, single cantilever and double cantilever different structural forms