Abstract: The temperature differential characteristics of inner and outer faces of absorbing cavity used in absolute calorimeter laser energy meter is studied theoretically and verified experimentally. Firstly, with the thermal conduction equations of second homogeneous boundary and nonhomogeneous boundary condition,we gained the temperature distribution in and after the heating process of the absorbing cavity. Secondly, through the simulation for the process of laser heating of the absorbing face, we obtained the expermental data of the temperature difference.In the end, with numerical simulation method, the theoretic results are analyzed numerically. The experimental data is very close to the theoretic analysis result, which proved that though fixed temperature difference is existed during laser heating, it will be soon reduced and the absorbing cavity will reach the heat balance after laser heating is finished.