NOVELTY - An organic wastewater is treated by transporting an organic wastewater comprising sulfate, nitrate, and organic pollutants to a fluidized bed reactor; adding activated sludge into the fluidized bed reactor, reacting, maintaining the pH value of the fluidized bed reactor; and adding microelement solution, reinforcing holophytic denitrifying devulcanized microorganism having a theoretical productive rate, and an acid-forming bacteria to transform organic matter in the fluidized bed reactor to micromolecular organic acid.    USE - Method of treating an organic wastewater (claimed).    ADVANTAGE - The method can synchronously remove carbon, nitrogen and sulfur in one reactor; has high treatment efficiency, conversion rate of more than 80% for sulfate and nitrate, and removal rate of organic matter of almost 80%; does not produce secondary pollutants; and prolongs service life of treating equipment.    DETAILED DESCRIPTION - An organic wastewater is treated by:    (A) transporting an organic wastewater comprising sulfate and nitrate having a mixing ratio of 0.5:5 (preferably 2:2.5), and organic pollutants with a chemical oxygen demand of 3-8 to a fluidized bed reactor, adding activated sludge into the fluidized bed reactor at a rate of less than 2 kgN/m3-d, reacting at 20-35 degrees C for 4-6 hours, maintaining the pH value of the fluidized bed reactor at 7.5-10;    (B) adding microelement solution (1 ml), reinforcing holophytic denitrifying devulcanized microorganism (200-800 mg/l of sulfide) having a theoretical productive rate of 65%, and an acid-forming bacteria to transform organic matter in the fluidized bed reactor to micromolecular organic acid; and    (C) allowing heterotrophic sulfate reduction-oxidation cell to convert sulfate to sulfide, allowing holophytic denitrifying microorganism takes nitrate as the electron acceptor to oxidize the sulfide to sulfur, and allowing heterotrophic denitrifying microorganism take organic acid as electron donor to denitrify the nitrate into nitrogen to separately transform organic matter, sulfate and nitrate in the raw water into carbon dioxide, elemental sulfur and nitrogen.