Half-open pipe is commonly used at the inlet of separators,and its structure and layout have a vital impact on the separation effect.In order to study the influence of half-open pipe layout on gas-liquid separation,this paper takes the separator of a domestic offshore platform as the research object,and uses numerical simulation software to simulate and analyze the half-open pipe models at different installation positions.The influence of different installation positions of half-open pipes on gas-liquid pre-separation effect is obtained,and some suggestions are put forward for the layout design of half-open pipes at the inlet of separators,providing theoretical support for the optimal design of separators.