In this article First Order Second Moment method and Monte-Carlo methods are used to calculate the reliability of the pipelines under uniform corrosion conditions. The results show that the data obtained by Monte-Carlo is a little lower than that by First Order Second Moment. Reliability assessment also shows that the reliability is continuously decreasing while the stress of the pipeline is still lower than yield limit of the material. At the 20th year of the pipeline''s use, the reliability is only 0.58, and the pipeline is not safe anymore. The parameters analysis of influence factors show that the thickness is the most important factor that influence the reliability, while yield limit is the second and load is the third. The influence of different loads to the reliability is decided by their awards to the total stress of the pipeline.