Abstract: SPE-HPLC was applied to the determination of 1-amino-2-naphthol-6,8-disulfonate in the Fenton′s degradation solution from azo dye orange G. Fe2+ were removed from the Fenton′s degradation solution by OnGuard Ⅱ H cartridges, C18 column was used as stationary phase and a mixture of acetonitrile and 10 mmol·L-1 NH4Ac (20+80) was used as mobile phase. UV-detection was made at the wavelength of 254 nm. Linearity range of 1-amino-2-naphthol-6,8-disulfonate was between 0.05-5.0 mg·L-1 with detection limit (3S/N) of 0.15 mg·L-1. Values of recovery found by standard addition method were in the range of 92.1%-99.2%, with RSD′s in the range of 2.8%-3.4% (intra-day), 4.1%-7.7% (inter-day).