Abstract: The fluctuation of coal-bed methane source parameters in coal mine is very volatile. In order to solve the negative influence of this fluctuation for coal-bed methane liquefaction device,relying on cryogenic liquefaction pilot plant for low concentration coal-bed methane,using the running test of cold box system,this paper theoretically studied the effects in the variation of raw material gas flux and methane concentration to device performance,noting that the re- covery rate of methane in LNG product is more sensitive to the raw material gas flux and methane concentration,but the change of raw material gas parameters has little effect on the purity of LNG product. In the design,for the adapta- bility to the change of raw material gas source,the following measures should be taken into account to ensure the nor- mal operation of the liquefaction device:the refrigerant leakage should be minimized in a mixed refrigerant cycle sys- tem;the mixed refrigerant filling system should be perfected to improve the degree of automation and designers should reduce the correlation between the top and bottom temperature regulation of distillation tower.