The work aims to establish a local corrosion model for oil and gas pipelines to solve the problem of operation safety and analyze the reliability of irregular areas. The pipeline corrosion in different irregular areas was firstly analyzed. Each area had local corrosion defects, and the failure of any area would lead to the failure of the whole pipeline network. Secondly, the finite element model of each region was defined. The local corrosion model and stress model given in the literatures were considered. Finally, the real corrosion parameters and time models were given by probability analysis, and the actual life of each area was obtained. Finally, three numerical examples with different corrosion rates were given to illustrate the influence of various factors on the reliability of corroded pipelines. Due to the influence of corrosion and residual stress, the reliability of irregular region was significantly greater than that of regular region. Considering the residual stress in different regions, the failure probability increased with the increase of residual stress, especially at high corrosion rate, the failure probability increased; while at low corrosion rate, the sensitivity decreased. The reliability of flange was more affected by whether there was residual stress corrosion. The conventional zone (base) had the best reliability. The response mechanism of irregular area to corrosion and residual stress is different from that of regular area. Compared with traditional method, the method proposed in this paper can evaluate the reliability of irregular area more effectively.