Abstract: In order to investigate the internal corrosion conditions of Sichuan-to-east gas transimission pipeline, the environment parameters of internal corrosion were investigated on the basis of the standard NACE SP0110-2010, and the source of water, water dew point, pipeline inclination angle and pigging history were analyzed. The results showed that internal corrosion had occured in the Sichuan-to-east Gas Transimission Pipeline.