A transformer assembly structure includes a transformer and a carrying seat. The transformer includes a bobbin, a winding coil assembly and a magnetic core assembly. The winding coil assembly includes a primary winding coil and a secondary winding coil. The carrying seat includes a main body and a first lateral wing. The main body has an edge. The first lateral wing includes a first positioning structure. The edge of the main body of the carrying seat is located at an inner side of an outer edge of the magnetic core assembly. The outlet part of the primary winding coil is managed and positioned by the first positioning structure.