Abstract: Increasing use of ethanol blended gasoline will make ethanol a new contaminant along with benzene，toluene，ethylbenzene and xylene isomers（ collectively denoted as BTEX） in groundwater. This study focuses on the effects of ethanol nitrate-enhanced bioremediation on permeability of porous media via four sand column experiments. Results showed that the removal rates of ethanol were greater than 92 % under limited dissolved oxygen and amended nitrate conditions. Effects of bioprocesses on permeability could vary with the initial concentration of ethanol, biodegradation rate and amendment frequency. For the initial concentration of ethanol near 1 000 mg/L or 3 000 mg/L，the permeability coefficient could continuously decrease one order of magnitude（ ×10-1 cm/s） comapred with the background value. The amendment frequency of ethanol was high because ethanol could be rapidly consumed within a short time. In the presence of the initial ethanol concentration up to 5000 mg/L，the permeability coefficient could decrease two order of magnitude. However, the slow consumption rate of ethanol and the low amendment frequency for ethanol would likely cause the permeability to be increasd. For comparison，dissolved hydrocarbons of gasoline without ethanol showed insignificant effect on permeability.