The effect of Hangang cold-rolling wastewater treatment by Gaia-BAF technology has been studied. The running parameters are optimized according to the experimental data. The research shows that under the continuously influent water conditions and when the hydraulic retention time is 10 h and 20 h respectively， the average removal rates of COD of the main pollutants by Gaia-BAF technology reach 92.2% and 90.4% respectively， and the average removal rates of ammonia-nitrogen reach 96.3% and 96.8%. Under the same influent water conditions， when the hydraulic retention time is 10 h， the removal rate of effluent water COD by Gaia-BAF technology is better than the effluent water in biological contact oxidation tank （hydraulic retention time is longer than 20 h）. The ammonianitrogen and chroma are basically the same as in biological contact oxidation tank.