Abstract: Based on the structural principle,existing testing methods and economic cost of the on-board LNG cylinder for vehicles,the experimental research on the rapid testing of the thermal insulation performance of the LNG cylinder by the constant pressure method.A fast test method for the thermal insulation performance of LNG cylinder with constant pressure method was introduced,and relevant test research was carried out.The results show that under the pressure of gas cylinder,the specific algorithm with laminar mass flowmeter and pressure controller can effectively reflect the adiabatic performance of the gas cylinder and significantly improve the detection efficiency.