As a highly reliable hermetic sealing method, parallel seam welding sealing has an increasingly important application in the ceramic packaging industry. For thin-walled ceramic package, the structural strength itself is relatively weak, and the high energy instantaneously generated during the seam welding process will cause thermal shock to the ceramic package while completing the sealing. In the subsequent reliability test, the residual stress is accumulated and finally released, resulting in a reduction in the structural strength of the casing, and finally air leakage or even porcelain cracking. In this paper, the thermal effect of the thin-walled ceramic package during the parallel seam welding process is simulated and analyzed by using Abaqus finite element analysis software. The influence of the parameters in the parallel seam welding process on the thermal effect of the ceramic package is mainly studied. The thermal stress distribution state of the package under different parallel seam welding parameter conditions is analyzed, which provides a theoretical basis for the sealing reliability of thin-walled packages. The simulation results are verified experimentally. A thin-walled CSOP16 line ceramic package was used to conduct multiple batches of sealing tests, and the sealing parameters were optimized and adjusted from the perspective of pulse width and period. The energy tolerance threshold of the parallel seam welding sealing of thin-walled packages is summarized, and the thermal shock caused by the parallel seam welding process to the ceramic package is reduced through experimental research, so that the thin-walled packages can meet the requirements of sealing reliability test after parallel seam welding. . The problem of porcelain cracking in the sealing of this type of package is solved, and a process specification is formed to guide the sealing process of the thin-walled package.