Vapor cell is the core component of the quantum instruments, and its stability and service life mainly determine the long-term reliability of the quantum instrument. During the preparation of vapor cell, the residual stress generated by high-temperature welding can affect its mechanical and optical properties. Excessive stress may lead to the explosion of vapor cell during processing. The crack caused by stress release may lead to its failure in use. The measurement and elimination of residual stress is great significance for improving the stability and service life of vapor cell. In this paper, a birefringence stress meter was employed to nondestructive test the stress in vapor cell. After annealing treatment, the maximum value, average value and standard deviation of the measured stress decreased in vapor cell shell by 81.35%, 75.67% and 77.32%, respectively.