The triphase AC sliding arc non-balancing plasma sewage treating apparatus includes one triphase AC high voltage power source, one water cooled glass reaction kettle, three knife metal electrodes connected separately to three phase line of the triphase AC plasma power source, one insulating cover, one atomizing nozzle and other parts. The sewage from the sewage source and the carrier gas from the carrier gas source are sprayed in the atomizing nozzle to form gas-liquid mixture entering to the water cooled glass reaction kettle, and the gas-liquid mixture drives the high voltage puncture arc to slide fast downstream and to form sliding pulse arc discharge in the surface of the electrodes, so as to generate non-balancing plasma including O, OH, H2O2, HO2., H, other active particles, ultraviolet ray, etc to degrade organic pollutants in sewage.