Objective To establish a UV spectrophotometry method for determination of diphenylamine in air of workplaces.Methods The air samples were collected by glass fiber filter treated with sulfuric acid,desorbed with alcohol by ultrasonic for 10 min,determined by UV spectrophotometry.Results The detection range of the method was 0.19-60 mg/m3(the air volume was15 L).The regression equation:y=0.13x-0.016.The correlation coefficients was 0.999 9.The detection limit was 0.28 ?g/ml.The relative standard deviations was 1.9% -8.4%.Sample-collected efficiency was 99%,desorption efficiency was 98% and the penetration capacity was more than 2.2 mg.Sample stability was 10 days at least by being stored in a refrigerator at 4℃ or by ambient storage.Conclusion This method is applicable to the determination of diphenylamine in air of workplaces.