Abstract: Reduced graphene oxide-silica gel composites were prepared by hydrothermal method and used as adsorbents of solid phase extraction column. A new method was developed for sensitive determination of sulfonamides in milk by solid-phase extraction coupled with high-performance liquid phase chromatography. The extraction conditions were optimized as follows: 0.1 mL methanol-acetic acid solution（V∶V′=1∶1.5）was selected as eluent and the volume of sample were 75 mL. The developed method showed a wide linear range of 0.1~100 μg/L and low detection limits of 0.027~0.078 μg/L. The method was applied to determine sulfonamides in milk with recoveries of 88.3%~113.6%