The invention relates to a support structure of a three-phase autotransformer switch. The support structure of the three-phase autotransformer switch comprises a first support plate (2) connected with core clamping parts (1), a second support plate (3) and a third support plate (4), wherein the second support plate (3) and the third support plate (4) are connected to the first support plate (2); and the three support plates all are of a rectangular frame structure with an opening in one side for accommodating the transformer switch, the side, opposite to the opening side, of the first support plate (2) is connected to the core clamping parts (1), one end of the opening side of the first support plate (2) is connected to the sides, opposite to respective opening sides, of the second support plate (3) and the third support plate (4) separately through two sides adjacent to the opening side, and the opening sides of the three support plates are parallel. The support structure of the three-phase autotransformer switch is convenient to produce and process, operation of a worker of a workshop is facilitated, meanwhile, the whole structure of a transformer is reduced, the strength of the transformer is improved and the support structure can bear relatively large switch weight.