A new method for the automated determination of three kinds of trace aromatic amines(o-toluidine，3,3′-dimethylbenzidine，β-naphthyl amine) was developed using on-line hollow fiber liquid phase microextraction/high performance liquid chromatography. An online detection device was built by connecting the hollow fiber liquid-phase microextraction device and high performance liquid chromatography with sequential injection device. The influences of extraction parameters including extracting solvent，donor phase，acceptor phase，salt effect，stirring rate and extraction time were investigated with this online device.The optimum experimental conditions were as follows:extraction reagent:1-octanol，donor phase:0.1 mol?L-1 NaOH-300 mg?L-1 NaCl，acceptor phase:0.1 mol?L-1 HCl， stirring rate:400 revolution per minute(r/min),extraction time:40 min.Under the optimum conditions，the qualitative and quantitative analyses of three kinds of trace aromatic amines were preformed by HPLC.The proposed method provided enrichment folds of 48-96.Good linearities were obtained in the range of 0.01-0.25 mg?L-1 with correlation coefficients not less than 0.998 4.The detection limits(S/N=3) were in the range of 0.3-2.2 μg?L-1 ,and RSDs(n=10) were 3.1%-4.0%.The spiked recoveries of aromatic amines in printing and dyeing wastewater ranged from 98.0% to 102.0%.With the advantage of simplicity，rapidness，less consumption of extracting solvent，high enrichment factor，and great precision for detection,this method is effective for fast and accurate analysis of trace aromatic amines.