Recently pipelines are constructed in parallel with high voltage power lines due to industrial development. It results in AC interference which gets more and more attention because it can result in electric shocks and accelerate corrosion of pipelines. Mitigation system is very important by decreasing AC potential and decelerating AC corrosion. Design of mitigation system is complex and many factors affect it. This paper describes some factors influencing mitigation system: trend of mitigation wires (parallel or vertical) length of mitigation wires interval of mitigation wires location of mitigation wires number and interval of connection between mitigation wires and pipelines diameter of mitigation wires soil type. The results can provide the reader with suggestions that make the design of mitigation system more effective and more costly.