Abstract: For problems that the choice of pumping time and pump type of beam tube monitoring system with long gas pipeline lacks theoretical support and only depends on experience, so as to lead large error, flow conductance of beam tube and effective pumping speed and pumping time of beam tube vacuum system were calculated through discriminating gas flow state in gas pipeline. Three kinds of vacuum pump and gas pipeline with four length were selected for combination experiment to verify accuracy of theoretical calculation conclusion. Based on calculation and experiment results, suggestions for selecting gas pipeline and pump in beam tube monitoring system are put forward.