Abstract: In order to research the maintenance problems of the submarine pipelines with pitting corrosion, this paper puts forward a method for calculating the variation of pipeline failure probability and reliability index over the time for different pipe materials and surrounding environments. By virtue of this method, the ultimate failure probability and reliability index under the constraint of reliability were calculated. Then, the incomplete preventive maintenance model for the submarine pipelines with pitting corrosion was established. In this model, the effect of each pipeline maintenance is characterized using virtual age and improvement factor, and the sensitivity analysis is carried out on the improvement factor, so that it can accurately reflect the effect of pipeline maintenance. Finally, the method for calculating pipeline life and cost was put forward. In addition, the above mentioned methods were applied to a case calculation of one certain submarine pipeline which had been in operation for many years, and the pipeline life and maintenance cost under different maintenance cycles were compared. It is indicated that the model can provide the best preventive maintenance cycle at a more reasonable cost while reflecting the pipeline maintenance effect accurately. The applicability and correctness of this method is verified.