Abstract: The South-West Multi-product Pipeline, from Maoming, Guangdong Province, to Kunming, Yun'nan Province, with the total length of 1620 km, is more complicated in operation way in China, for which a specific software is developed by University of Petroleum, Beijing, China. The software plays a very important role in the start-up of the pipeline. The differential between the results by the software and field data is acceptable, thus, the software can provide technical support for the operators of the pipeline.