Abstract: Aimed at the corrosion of west to east gas transmission pipeline in Yakela gas field founded during excavation,ultrasonic thickness and wall probe sounding technology were used to detect the corrosion of excavated pipelines.Combined with the pipeline medium conditions,surrounding soil and terrain conditions,the corrosion of pipeline anti-corrosion layer,the corrosion products,the corrosion characteristics,the corrosion factors and mechanism were observed,tested and analyzed.The results showed that the cause of pipeline corrosion was dissolved oxygen corrosion in soil containing water under the failure condition of anti-corrosion layer and cathodic protection corrosion.Combined with the pipeline design,operation parameters and test data,the safety evaluation and prediction of residual life of the pipeline were conducted.The results showed that the pipeline upstream within 3.5 km was in a non secure area,needing corrosion control.Aimed at the corrosion problem,specific measures were put forward.