The invention provides a unified electric energy quality controller. The unified electric energy quality controller comprises a serial unit and a parallel unit, wherein the serial unit comprises two serial converters and three transformers; the parallel unit comprises a parallel converter; three single-phase output ends of alternating-current sides of the two serial converters are respectively connected to terminals of the three transformers; same-phase output ends of the two serial converters are connected with the same transformer; obtained voltage is coupled through the three transformers and then is serially connected into each single-phase feeder line of a three-phase feeder line; direct-current sides of the two serial converters are respectively connected to a direct-current side of the parallel converter; and three single-phase output ends of an alternating-current side of the parallel converter are respectively connected to each single-phase feeder line of the three-phase feeder line. According to the unified electric energy quality controller disclosed by the invention, a module redundancy problem is effectively solved, and a voltage sag compensation capability and the working stability are higher.