The invention discloses a plugging-type three-dimensional bending iron core of a three-phase transformer. The plugging-type three-dimensional bending iron core comprises three unit bending iron cores with the same shapes and sizes, all the unit bending iron cores are octangle frames and formed by left unit iron core columns, right unit iron core columns, upper unit iron yokes and lower unit iron yokes, wherein the left unit iron core columns and the right unit iron core columns are same in height; the left ends and the right ends of the upper unit iron yokes of all the unit bending iron cores are installed on the left unit iron core columns and the right unit iron core columns in a one-to-one corresponding mode and a pluggable mode; all the unit bending iron cores are formed in the mode that a plurality of monomer bending iron cores with left monomer iron core columns, right monomer iron core columns, upper monomer iron yokes and lower monomer iron yokes are sequentially embedded respectively, and are made from silicon steel sheets. According to the plugging-type three-dimensional bending iron core, whole device-body assembling is completed through plugging-type installing of the upper unit iron yokes, the investment cost of the device is saved, and assembling of a three-dimensional transformer coil is greatly convenient.