Abstract: Based on the two-fluid model, a transient model for the simulation of transient process in multiphase pipelines with low loads of liquids was developed. The solution of the transient model as well as the model for the stratified flow was discussed deeply. Moreover, many experiments including pigging and flow rate changing were conducted on the large multiphase flow loop. The model gave very good simulation and accurate forecasts for all kinds of important parameters, which was very satisfying, when it was used to simulate experimental system and the actual multiphase pipeline.