A method for isolating the spread of power quality disturbance between the high-voltage and low-voltage side and controlling power quality problems in distribution network based on power router is proposed in this paper. Firstly, the main circuit topology and working principle of power router based on power electronic transformer is present, the control strategy for accessing to active power distribution network is designed. Secondly, the control strategy to isolate the spread of voltage distortion from high voltage side to low voltage side as well as the spread of load mutation and harmonic from the low voltage side to the high voltage side is proposed. Finally, the correctness and validity of the presented method is verified by PSCAD simulation. The results show that the proposed control strategy not only can achieve the original energy distribution and voltage isolation transformation function perfectly, but also can effectively isolate the spread of power quality disturbance between the high voltage side and low voltage side, which provide new train of thoughts for the research and practical application of power router.