The invention relates to a railway wagon for transporting trucks and a truck loading and unloading method. The railway wagon is characterized by comprising a middle running board device, end running board devices are respectively arranged at two ends of the middle running board device, and a bridge board device is arranged at the outer end of each end running board device; the middle running board device comprises a plurality of middle running board assemblies, each middle running board assembly comprises a running board connected with a side wall, and at least a support plate connected with the side wall is arranged below the running board; the end running board devices comprise a plurality of end running board assemblies, each end running board assembly comprises a running board connected with the side wall, and at least a support plate connected with the side wall is arranged below the running board; each bridge board device comprises a bridge board, one end of the bridge board is connected with the running board through a connecting plate, and the other end of the bridge board is connected with an underframe assembly; and a foldable support mechanism is arranged at the bottom of the bridge board. The devices provided by the invention are oppositely installed at the middle parts of two side walls of the railway wagon, so that the inner space of the railway wagon is reasonably utilized, the truck loading quantity is increased, and the transport efficiency is improved.