Objective To verify the stray current corrosion caused to the adjacent pipelines by the cathodic protection system when protecting the target pipeline, compare the stray current pollution generated by flexible anode and anode ground bed during pipeline protection process, and propose joint protection of different pipelines buried in the same ditch. Methods The different pipelines in same region were jointly protected through the same drainage device, using the grounding device of the cathodic protection system as the only anode, and the multiple buried pipelines as the cathode of the electrochemical cell. Results The stray current interference caused by the anode ground bed was obviously stronger than that of the flexible anode material. In drainage protection, when the two 20 m buried metallic pipelines reached the range of drainage protection, the drainage voltage of the flexible anode was 1. 2 V to 1. 52 V, which was far smaller than that of the carbon steel anode ground bed (3. 5 ~ 15 V), effectively reducing the power consumption during the protection process. Conclusion The drainage protection of multiple metallic pipelines or metallic structures using the same cathodic system was feasible.