The invention belongs to an electromagnetic shield plate, a preparation method thereof, and a modular assembling electric cabinet provided with the electromagnetic shield plate. The modular assemblingelectric cabinet comprises a damping base unit, the damping base unit is connected with a frame unit, one side of the front surface of the frame unit is connected with a cabinet door through a hinge,and the cabinet door is provided with a mechanical lock matched with the other side of the front surface of the frame unit; an upper cover is arranged at the top of the frame unit, and a baffle mechanism slidably connected with the upper cover is arranged at the bottom of the upper cover; and the baffle mechanism comprises a sliding block mounted at the outer circumference of a screw rod at the bottom of the upper cover in a sleeving mode, the sliding block is provided with an adjusting knob matched with the screw rod, and the bottom of the sliding block is connected with the electromagneticshield plate. The modular assembling electric cabinet has the advantages that the structure is simple, design is reasonable, using is convenient, assembling and disassembling are convenient, quick mounting is convenient, transporting is also convenient, meanwhile, the good damping and partition mounting functions are achieved, and the service life of power distribution elements in the electric cabinet is effectively prolonged.