In order to improve the output laser polarization stability of high-energy polarization fiber lasers, the signal light source and (6+1)×1 reverse polarization-maintaining optical fiber coupler were combined by introducing the basic principle of reverse extinction ratio of reverse polarization-maintaining optical fiber coupler. The influence of signal polarization-maintaining optical fiber diameter and physical change of the stress area of the reverse polarization-maintaining optical fiber on the reverse extinction ratio of a reverse polarization-maintaining optical fiber coupler was studied. The results show that the smaller the diameter of the signal polarization-maintaining fiber, the more stable the polarization state of the output polarized laser, and the reverse extinction ratio is greater than 49 dB. At the same time, the coupling efficiency of the pumping fiber arm of the reverse polarization-maintaining fiber coupler is improved to more than 98%. The more serious the change of the physical structure of the stress region of the forward polarization laser output fiber, the less stable the polarization state of the output polarization laser. The research provides reference for the preparation of high extinction ratio high-energy polarization fiber lasers.