The work aims to analyze corrosion characteristics of a typical pipe section of natural gas pipeline, and clarify the cause and mechanism of pipeline corrosion. Scanning electron microscope (SEM) was used for surface and section microscopic observation of corrosion morphology in different positions on inner wall of the pipeline. Quantitative analysis of the composition was carried out in X-ray diffraction and EDS method. Corrosion characteristics in the natural gas pipeline were studied by referring to such service conditions as natural gas composition delivered by the pipeline and pigging records. CO2 corrosion was the main cause of corrosion in this natural gas pipeline. The corrosion pit in 12 o‘clock direction was about 0.18 mm deep, and that in 3 o‘clock and 6 o‘clock direction was about 0.1 mm. The corrosion products were mainly Fe2O3 and FeCO3. The corrosion products in 6 o‘clock direction was the thickest, and those in 3 o‘clock direction were the thinnest. The corrosion products in 3 and 6 o‘clock direction were mainly Fe, O and C, and the corrosion products in 12 o‘clock direction contained S and may be subject to bacterial corrosion simultaneously, SiO2 was contained in the residual sludge in the pipeline itself, the pipeline may have been corroded before it was put into operation. Relevant corrosion prevention and control measures were put forward specifically, and frequency of pipeline replacement decreased by 56% after adoption of the measures. Internal corrosion of natural gas pipeline is mostly localized corrosion. During operation, corrosion shall be avoided as much as possible, and appropriate control measures shall be taken in time to avoid unnecessary losses.