Abstract: The severe slug flow occurred in the multiphase pipelines among 8-3A platform, 14-3A platform and 116FPSOof Wenchang oilfield group was theoretically analyzed and experimentally studied. The flow state in 14-3A sea pipe wastheoretically analyzed according to the judging criterion of severe slug flow. The experimental platform for pipeline S-shapedriser with severe slug flow was designed and reconstructed based on the size of the sea pipe, and the flow patterns of oil, gasand water in the sea pipe and their transformation processes were simulated. A set of automatic control program of throttlevalve based on pressure signals along the pipeline was put forward according to slug flow elimination theory and classicalPID control theory, and it effectively eliminated the severe slug flow in the experiment. After the transformation of 116FPSOis conducted, this technology is applied in Wenchang oilfield group. And owing to its application, the fluctuation amplitudesof lower sea pipe pressure and upper FPSO pressure are reduced significantly, and oil and gas production is improved.