The invention relates to a large-capacity dual-body phase-shift transformer which comprises a series transformer oil tank, an exciting transformer oil tank, a series transformer, an exciting transformer, and a resistance type on-load tap-changer with a polarity selector. Each phase of the series transformer consists of a high voltage coil and a low voltage coil; each phase of the exciting transformer consists of a high voltage coil and a phase-shift coil; and a tapping cap of the phase-shift coil of each phase of the exciting transformer is in contact with a static contact of the resistance type on-load tap-changer of the phase, and two ends of the phase-shift coil of the phase are connected with the positive and negative ends of the polarity selector of the phase. A mobile contact of thepolarity selector is connected with one end of the low voltage coil of the corresponding phase of the series transformer. The transformer has the advantages that: the transformer solves the problem of over current caused by transmission lines connected in parallel, thereby bringing about stability and high efficiency for the run of an electric system.