Abstract: A spiral groove dry-gas seal generates a finite amount of heat in high speed running, which will lead to the thermo-elastic deformation of a sealing ring. The thermo-elastic deformation has an impact on the sealing performance. The gas film pressure and velocity of a spiral groove can be obtained based on the boundary conditions of a slip-flow, and the energy equation considering the thermal dissipation of the gas film is derived. The temperature distribution of the gas film can be solved out by using the film pressure, the velocity and energy equation under the help of software Maple and Matlab. Based on thermo-elastic deformation theory, the deformation formula of a sealing ring and a gas film-thickness formula can be obtained. And the theoretical leakage rate can be obtained by using the general Reynolds equation, which will be compared with the experimental leakage rate. The results show that the temperature of the groove is increasing firstly and then decreasing when the gas flows from the external into the interior, the temperature is higher next to the groove root. The changed trends of the thermo-elastic deformation and temperature are consistent, and the trend of gas film thickness is opposite compared with the thermo-elastic deformation. With the increase of deformation, the leakage rate is large, and the leakage rate of the thermo-elastic deformation considering the thermal dissipation is closer to its experimental value.