The work aims to study internal corrosion direct assessment standard proposed by National Association of Corro-sion Engineers (NACE) for multiphase flow pipeline: SP0116-Multiphase flow internal corrosion direct assessment methodology for pipelines (here in after referred to as MP-ICDA) and explore the application steps of this method in the domestic field, so as to provide some reference for the domestic internal corrosion direct assessment method. Norsok M506 internal corrosion predictive modeling was established based on the actual working conditions of the pipeline in the east sea in China to simulate and analyze the internal corrosion conditions of pipeline through the hydrodynamics theory. The internal corrosion direct assessment was carried out by four steps: pre-assessment, indirect inspection, detailed examination and post-assessment. When the whole internal corrosion rate of pipeline was greater than 0.25 mm/a, the corrosion degree was serious. The corrosion rate of low-lying part at 1.5~2.5 km and the inlet and outlet risers increased obviously. The high risk points of corrosion were related to the flow parameters such as slug flow state and liquid holdup. The on-line detection results were basically consistent with the model prediction results, thus proving the reliability of the model. According to the level of corrosion and the standard period of re-assessment of the internal corrosion, the pipeline re-assessment interval was one year. ICDA method can accurately predict the condition and risk of corrosion and provide an effective method of internal corrosion assessment for subsea pipeline not suitable for internal inspection. It has a certain guiding effect and reference significance for the prediction of the location and risk level of corrosion in multiphase flow pipelines. The kinetic parameters of the fluid have great influence on the corrosion rate. When the MP-ICDA method is adopted, the appropriate internal corrosion prediction modeling and pipeline operating parameters should be selected. During the normal operation by subsea pipeline, ICDA can be checked for several times to improve the accuracy of corrosion prediction.