The degradation of phenol was investigated in a continuous flow impinging streams system. In the first step, statistical experimental designs were used to optimize the process of phenol degradation in a photo-impinging streams reactor. The more important factors affecting phenol degradation (p<0.05) were screened by a two-level Plackett-Burman design. Four of the latter parameters, namely phenol concentration, catalyst loading, pH and slurry flow rate, were selected for final process optimization, applying central composite design (CCD). The predicted data showed that the maximum removal efficiency of phenol (99%) could be obtained under the optimum operating conditions (phenol concentration=50 mg l^(-1), catalyst loading=2.1 g l^(-1), pH 6.2 and slurry flow rate=550ml min^(-1)). These predicted values were then verified by certain validating experiments. A good correlation was observed between the predicted data and those determined by the experimental study. This may confirm the validity of the statistical optimum strategy. Finally, continuous degradation of phenol was performed, and the results indicated a higher efficiency and an increased performance capability of the present reactor in comparison with the conventional processes.