Abstract: With the exploitation development of Chuanyu gas field, the period has come to its mid-late stage. It is common that gas and water are produced simultaneously, in which there exists the corrosive medium such as H₂S/CO₂. During the exploitation process in H₂S-containing gas well, the pipe string of downhole plays an important role of controlling production and protecting the safety of the underground tubing system. The complex corrosion environment in downhole can lead to severe corrosion of pipe string, and even cause material failure. Therefore, in the period of normal production, the monitoring and detection of downhole pipe string can provide data support to corrosion control and safe production. This paper focuses on the application of electric resistance probe, multi-arm caliper tool plus magnetic wall thickness gauge in Chuanyu gas field, and provides an advice on combination technology utilized in downhole pipeline in gas well.