The working environment for high-temperature seals used in aerospace vehicles is harsh,and performance testing of seals is necessary to ensure flight safety.However,the existing testing equipment and methods cannot achieve the ideal high-temperature,high-pressure,and variable simulation working environment.Taking the airtightness testing of W-shaped metal sealing rings as an example,a seal tester was designed and a high-temperature thermal sealing test platform was build.Transient thermal analysis was carried out on the tester model to obtain the temperature field distribution and total structural deformation of the tester.The continuous and automated leakage rate testing of W-shaped metal sealing rings was carried out at various temperatures from room temperature to 740 ℃,with the internal and external pressure difference from 0 to 1.2 MPa.The results show that the test piece is uniformly heated in the tester and can reach the required maximum temperature of 740 ℃.The tester can withstand an internal pressure of 1.1 MPa and has no plastic deformation under high temperature conditions.The proposed testing technology can effectively evaluate the sealing performance of different W-shaped metal sealing rings,and can achieve airtightness testing of W-shaped seals under various pressure and temperature conditions.