Abstract: Objective As traveling wave tube (TWT) devices enter the fields of ultra-high frequency, high power and long life, higher requirements have been imposed on the reliability of the ceramic-metal sealing process. The commonly used sealing form in TWTs is 95%Al₂O₃/4J33. Multiple welding processes are required during the manufacturing process of TWT, and the joints have to withstand multiple thermal shocks of 298～1023 K. The aim of this paper is to study the effect of thermal shock on joint quality and mechanical property. Methods Standard specimen are designed and multiple thermal shock tests are conducted on the joints of standard specimen to compare the changes in the microstructure of the joints. The thermal shock simulation of the standard specimen is also carried out. Results It is found that ten thermal shocks do not change the joints structure, but the size of shrinkage porosity in the solder is significantly increased, while the mechanical properties of the joints decreases with the increase in the number of thermal shock. Conclusion The thermal shock increases the tensile stress at the interface between the metallization layer and the solder layer, reduces the interface strength, and promotes the expansion of the original porosity defects in the solder.