Accurate measurement of the internal stress in high-end glass relates to the safety and reliability of the system in which it is used. This paper proposes a stress measurement method based on the laser feedback effect. The laser feedback system consists of a laser and an external mirror. The sample to be measured is placed in the external cavity of the feedback system, and the polarization flipping of the laser induced by the gain modulation of feedback light is used to extract stress information. First, the relationship between the phase of the orthogonally polarized modes of the laser and the birefringence of the external cavity was theoretically analyzed. Next, the phase information of the orthogonally polarized tuning curve was obtained by Fourier transform. Then, the precision of the system and algorithm was tested using a standard quarter-wave plate. Finally, the laser feedback system was used to measure the internal stress in various aircraft cockpit plexiglass samples and measurement results are given. The experimental results show that the measurement accuracy of the system for fringe number is better than 8.3×10-4, which meets the stress detection requirements of high-end glass.