Taken 12 000 t lifting buoyancy salvage engineering ship for example, the heat dissipation of stern shaft bearing is studied with the thermodynamics module of finite element analysis software COMSOL Multiphysics. The shafting arrangement and empty compartment of stern tube are introduced, the heat balance and working pressure distribution of stern shaft bearing under the condition of oil film establishment are analyzed, and the thermodynamic finite element simulation of shafting and empty compartment of stern tube is made. The simulation results meet the relevant requirements of stern shaft bearing, and are verified in the actual ship trial, which shows that the conventional stern tube cooling water tank can be eliminated.