Abstract: Before the cryogenic fluid is transmitted through the pipe network system,the pipe network system should be fully precooled to avoid the occurrence of gas-liquid two phases in the transportation process of the cryogenic fluid.Based on the flow boiling model of Steiner in AMESim,liquid nitrogen is used as precooling working medium to analyze the precooling process of pipeline system,and the effects of inlet pressure,pulse flow frequency and pulse ratio on the precooling effect are emphatically explored.The simulation results show that within the calculation scope,the precooling efficiency of the pipe network gradually decreases with the increase of the inlet pressure,so the inlet pressure can be appropriately reduced to improve the precooling efficiency when the fluid delivery requirements are met in the actual precooling process.In addition,the precooling efficiency of pulse flow increases first and then tends to be stable with the increase of pulse frequency,and decreases with the increase of pulse ratio.The research results have a certain guiding significance for improving the precooling efficiency,reducing resource consumption and ensuring the safe precooling process.