To improve the reliability of the integrated navigation system and the accuracy of pose estimation, a novel visual inertial integrated navigation system assisted by polarized light is proposed and constructed by introducing a polarization orientation sensor into the process of simultaneous localization and mapping. The data from the polarization orientation sensor, monocular vision camera, and micro-inertial measurement unit are collected. The target equation is established using the least square optimization method after multi-sensor data has been time-stamped aligned and preprocessed, and the best motion estimation is then produced by solving nonlinear equations. In the suggested system, the observability of azimuth is achieved based on the polarization distribution of the sky, and multi-sensor data are fused. Based on the above-integrated navigation system, an outdoor vehicle-mounted experiment is carried out. The experimental findings indicate that, in the long-distance operation of 2 km, the location inaccuracy of the polarized light-assisted visual-inertial navigation system is 16.7% lower and the heading angle accuracy is 23.4% greater than the estimated value of the original visual-inertial system. The polarization orientation sensor can reduce the drift of inertial devices, enhance the position accuracy and attitude angle accuracy of the navigation system, and meet the needs of the position and pose estimation accuracy and reliability under the interference of satellite signals.