Provided in the invention is a three-stage type alternating-current/direct-current hybrid three-port power electronic transformer comprising three filter inductors LgA, LgB, and LgC, three cascaded converters CCA, CCB, and CCC, six low-frequency blocking capacitors CLFB1, CLFB2, CLFB3, CLFB4, CLFB5 and CLFB6, three high-frequency isolation transformers THF1, THF2 and THF3, and a three-phase four-wire inverter INV. According to the three-stage type alternating-current/direct-current hybrid three-port power electronic transformer, with the cascaded converters CCA, CCB, and CCC, direct AC/AC conversion form the low-frequency alternating current to the high-frequency alternating current is realized; with the high-frequency isolation transformers THF1, THF2 and THF3, direct AC/AC conversion ofthe high-frequency alternating current of electric energy is realized; and with the three-phase four-wire inverter INV, direct conversion from the high-frequency alternating current to the low-frequency alternating current and direct current is realized.