Abstract: According to the characteristic of temperature field, density lock can be divided into mixing zone, conductive zone and constant zone, and heat transfer model was established in each zone. The steady-state heat transfer models were evaluated by comparing with the experimental results. It is showed that the temperature field in density lock can be well predicted by the heat transfer model at steady-state. The correlation for calculating the heat loss in density lock was deduced. The minimization of heat loss was also discussed in the paper.