Oil flushing, also known as oil cleaning, is a common process in the construction of offshore platforms. In particular, the hydraulic system has a high requirement for pipeline cleanliness, and usually the pipeline has many branches. So it is difficult to divide the oil flushing package into single line circuits, and the oil flushing quality of each branch cannot be guaranteed. This paper builds models according to parameters of the pipeline system, proposes to analyze the feasibility of the procedure using fluid software simulation before oil flushing operation. Adjusts the oil temperature, kinematic viscosity, flow control and other aspects, and then optimizes the oil flushing procedure to ensure the quality and improve efficiency.