Abstract: First, a method of determining the inner- diameter of liquid hydrogen injection tubes is presented for a typical heat leak. Proper injection tubes are used to estimate the consumption of liquid hydrogen, thereby to reduce the cost of experiments. The liquid hydrogen is mainly consumed in the following three ways, by pre-cooling tubes, by overcoming flow resistance and by heat leak. Second, an insulation structure is designed for the above heat leak. Third, a liquid hydrogen injection tube is designed and manufactured by this method for an experimental container. At last, a comparison between theoretical and experimental parameters is made with respect to the injection efficiency and the pre-cooling liquid consumption.