Abstract: By comparing the process simulation data and experimental data of crude flash point, it is found that using PRO/II V9.4 software API 2B7.1 (2007) to simulate flash point of crude has the minimum simulation deviation. Based on the simulation results, the selection of vacuum pump unit of crude vacuum flash evaporation equipment is carried out for an oil field in the South China Sea. By analyzing the operating parameters of vacuum pump, the combination of an NC-0630B dry screw vacuum pump, two ZJY-1200A Roots pumps and two ZJY-2500A Roots pumps is selected, which can meet the requirements of process.