The invention discloses a loaded welding superimposed steel plate structure and a machining technology thereof. The loaded welding superimposed steel plate structure comprises an operation platform, the upper surface of the operation platform is provided with a bottom layer steel plate, and an upper layer steel plate is placed on the bottom layer steel plate; a pressing beam is connected to the top of the upper layer steel plate, and screw jacks are placed on the upper portion of the pressing beam; the tops of the screw jacks support platform frames upwards, and the two bottom ends of each platform frame are connected to the operation platform; and an upper connection plate is arranged on the platform frames and welded to the platform frames. Through the loaded welding superimposed steel plate structure, steel plate welding deformation caused by long welded seams can be effectively reduced, multi-layer steel plate superimposing welding hollowing, welding deformation and welded seam staggering are relieved, the quality of a finished steel structure component product is improved, and the safety of the main body structure construction process is improved.