Abstract: The present invention belongs to the technical field of sewage denitrification. Disclosed are a sewage treatment system and method of continuous flow step-feed short-cut denitrification-anaerobic ammonia oxidation coupled with denitrification. The system comprises a primary sedimentation tank, a bioreactor and a secondary sedimentation tank, which are connected in sequence, wherein the bioreactor comprises a pre-starvation zone, a first hypoxic zone, a first aerobic zone, a second hypoxic zone and a second aerobic zone: an agitator is arranged in each of the pre-starvation zone, the first hypoxic zone and the second hypoxic zone; an aeration device is arranged in both the first aerobic zone and the second aerobic zone; a polyurethane sponge filler is arranged in both the first hypoxic zone and the second hypoxic zone; and a nitrification liquid reflux pump is arranged between the first aerobic zone and the pre-starvation zone.