The invention discloses a three-phase inter-coupling and five-port power electronic transformer. The three-phase inter-coupling and five-port power electronic transformer comprises: a three-phase modular multilevel conversion unit connected with a power grid and configured to rectify a medium-voltage three-phase alternating current of the power grid to a medium-voltage direct current and output the medium-voltage direct current; a high-frequency isolation DC/DC conversion unit, wherein a primary is connected with the sub module direct current capacitor of the three-phase modular multilevel conversion unit, the voltage of the sub module direct current capacitor of the three-phase modular multilevel conversion unit is converted to a low-voltage current through high-frequency isolation for output, and the output end of the high-frequency isolation DC/DC conversion unit is connected with a low-voltage direct current bus; a DC/AC inversion unit having a direct current side connected with the low-voltage direct current bus to invert the low-voltage direct current to a three-phase alternating current and a single-phase alternating current for output; and a light storage device connected with the high-frequency isolation DC/DC conversion unit and the DC/AC inversion unit. The three-phase inter-coupling and five-port power electronic transformer can be better suitable in the current AC-DC hybrid power system to achieve bidirectional flow and electrical isolation of each port power at the same time.