Abstract: In order to comprehensively understand the corrosion status of X65 steel pipelines sealed with high content well water after restart, the parameters before and after sealing were compared and analyzed by on-site detection of dissolved oxygen, total iron, CO₂ content and H₂S concentration in the sealing solution, as well as bacteria (SRB, TGB, FB). The results show that there was no significant different in dissolved oxygen content after restarting the subsea pipeline compared to the storage of the pipeline, and dissolved oxygen corrosion was mild. The total iron content after the restart of the subsea pipeline was slightly higher than that before storage, with slight corrosion. The concentration of H₂S and CO₂ after the restart of the subsea pipeline had decreased compared to that before storage. The SRB, TGB, and FB content of 1 000/mL, 1 000/mL, and 1 000/mL after receiving the ball from the C subsea pipeline indicate that bacterial colonies had proliferated after being sealed in static high water containing wells. The overall corrosion of the subsea pipeline was slight. It is recommended to clean and disinfect the sealed subsea pipeline.