Abstract: Reciprocating liquid hydrogen pump is an important part of liquid hydrogen refueling station and an important part of green transportation. The liquid hydrogen pump is filled with low temperature liquid hydrogen, while the shell is exposed to the environment. The heat transfer loss of liquid hydrogen pump cannot be ignored. Taking a liquid hydrogen pump as the research object, this paper analyzed the heat transfer loss caused by radiation heat transfer and thermal conductivity of the liquid hydrogen pump through theoretical analysis, and established a three-dimensional thermal conductivity model of the liquid hydrogen pump to verify the accuracy of thermal conductivity calculation. The heat leakage is 34.96 W, which is about 0.3 kg/h of liquid hydrogen evaporation. The calculation results show that increasing the length of piston and cylinder and changing the structure of the chamber support can effectively reduce the static heat loss of liquid hydrogen pump.