Abstract: A filtration pillar filled with expanded graphite was designed as testing device for absorbing oil in waste water.The oil concentration in water was determined by a spectrometer with calibration curve.The oil concentration in filtrated water was about 6 mg/L to 15 mg/L at the very beginning,and soon reached lower than 5 mg/L ,a very satisfying level for the water to be poured back to underground.The influence of pore structure of expanded graphite on absorbing capability was analyzed.It was found that the absorbing capability of expanded graphite increased with the increase of compact density and decreased with the increase of flowing rate of waste water.