The invention discloses a multi-segment structure of a magnetic shunt for iron cores of a reactor. The multi-segment structure comprises a framework, the iron cores, the magnetic shunt and air gaps. The framework is a cuboid. The magnetic shunt is located in a symmetrical shaft of the framework. The more than two iron cores are disposed in the framework and symmetrically distributed on two sides of the magnetic shunt. An air gap is kept between every adjacent iron cores. The multi-segment structure of the magnetic shunt for the iron cores of the reactor has following beneficial effects: in the structure, the iron cores are of multi-segment assembling structures; by adding the air gaps between every two iron cores, temperature rise of a product is reduced; the product is small in size under the same power and is flattened; and the installation requirement in special space is satisfied.