To address the stray direct current interference on a natural gas pipeline due to Qingdao Metro Line 13, this paper aims to clarify the influence range, degree of impact and corrosion characteristics of metro DC interference, and verify the effectiveness of relevant mitigation measures. To clarify the scope and extent of interference of Qingdao Metro Line 13 DC stray current on the pipeline, and building on the evaluation of the effectiveness of the pipeline’s cathodic protection system, site investigations were carried out on mitigation measures on the stray current interference, including field corrosion coupon, temporary power feeding test and sacrificial anode etc. From the study, the following basic rules on the influence became clear, namely the affected area, the extent of the impact, pipeline electrical potential offset segmentation and its periodic changes and fluctuation; and the corrosion rate and characteristics of the corrosion coupon. Meanwhile, the effectiveness of mitigation measures such as adjusting the current output of the cathodic protection system and installing additional temporary sacrificial anodes was verified on site. A corresponding programme of cathodic protection system modification, mitigation by draining stray current and corrosion monitoring was then developed. The result of this research could provide a reference for future projects of the same nature.