Abstract: HPLC was applied to the determination of 5 residual sulfanilamides in fish,after its extraction with dichloromethane,de-fatting with n-hexane,and purification by solid-phase extraction on Waters Oasis HLB solid-phase extraction column.Sulfanilamides on the column were eluated with methanol,which was dried at 35 ℃ under reduced pressure.The residue was taken up with 1.0 mL of a mixture of CH3OH,CH3COOH and H2O (33+0.67+66.33),and the solution was used for HPLC analysis.HPLC separation was carried out on a Cloversil C18 column (250 mm×4.6 mm,i.d 5 μm),using a mixed solution of HOAC+CH3OH+H2O (1+10+89 by volume) as the mobile phase (phase A);and gradient elution with CH3OH at different volume ratios.UV detections were made at 265 nm.Linearity of the calibration curves of all the 5 sulfanilamides were in the range from 0 to 500 μg·L-1 with correlation coefficients largers than 0.999 3.Detection limits obtained were 0.1 μg·kg-1.Recoveries found were in the range of 78.6%-87.6%,and RSD′s ranged from 3.42% to 9.03%.