The invention discloses a coking wastewater treatment system and method. The method comprises the steps of preparing dominant bacteria and putting the dominant bacteria into a membrane bioreactor, wherein the membrane bioreactor comprises an aerobic activated sludge tank and a membrane separation tank. The method specifically comprises the following steps: (1) taking aerobic activated sludge out of a coking wastewater discharge port; (2) acclimating, separating and purifying the aerobic activated sludge obtained in the step (1), thereby obtaining the dominant bacteria; (3) putting the dominant bacteria obtained in the step (2) into an aerobic sludge tank to react; and (4) after the wastewater, which is subjected to degradation reaction, enters a membrane separation tank, carrying out sludge-water separation. The invention efficiently removes specific organic pollutants in the coking wastewater by using the active dominant bacteria, thereby achieving the goal of degrading organic pollutants in a simple, efficient and quick way, so that the wastewater can be discharged after reaching the standard.