Degradation of phenol in water using direct high voltage discharge was investigated. The effects of some factors, including the pressure of the oxygen input, oxygen flow rate, ground electrode diameter, and initial pH were studied on the removal rate of phenol. Higher oxygen pressure and alkaline circumstance improved the process of decomposition. Under the condition of ground electrode inner diameter of 29 mm, oxygen flow rate of 60 mL/min, the removal rate reached 90 % after 180-min discharge treatment. The solution conductivity was found to change with the removal rate of phenol accordingly.