Abstract: The geological conditions of buried pipelines in southwest mountainous areas are complicated, some pipelines are laid in parallel at the same pipeline corridor. Each pipeline adopts an independent cathodic protection system, the risk of mutual interference between the cathodic protection systems are exist. In this study, the influence of cathodic protection system on the target pipeline after power-off of the parallel pipeline cathodic protection system in southwest mountainous area was studied. The ground potential under mutual interference was continuously monitored for several months. The continuous monitoring of pipe-to-soil potential under mutual interference condition was sustained for several months. Two typical parallel pipeline segments and total of 5 test points were selected for corrosion rate analysis. The results showed that the natural corrosion rate of soil at this five locations is 0.080-0.217 mm/a, the corrosion rate under cathodic protection is 0-0.126 mm/a. The cathodic protection effect is good and corrosion risk is low, the corrosion rate of soil is several times or more than ten times of that under cathodic protection, and the influence of mutual interference between the parallel pipeline cathodic protection on the corrosion of pipeline is not significant.