Abstract: In this paper,a method of ultra-low temperature vacuum pipeline was proposed to measure the vacuum degree of liquefied natural gas(LNG)low temperature vacuum pipeline without the reserved detection port based on the temperature field principle of the vacuum degree test method.According to the temperature field principle,the vacuum pipeline system was designed and fabricated.The low-temperature vacuum pipeline system includes the inner tube,a heat-insulation layer,the outer tube,the temperature sensors,and the data acquisition system.The inner tube was filled with cryogenic liquid,and the inner layer and outer layer of the heat insulation layer were made of glass fiber paper and aluminum foil,respectively.The outer tube has a vacuum port and a vacuum gauge connection port,and a thermometer measures the temperature of the outer tube.Then the influence of pressure on the temperature of the low-temperature vacuum pipeline was simulated.Finally,the simulation results were verified by the vacuum system,and the experimental results achieved the expected goals.