Polarized light navigation is a interesting research hotspot in the world today. People study the mechanism of polarized light navigation for a long time. However, less progress has been done on the navigation precision. This article discussed on azimuth calculation and polarized angle measurement. Polarized angle measuring system is designed to detect polarized light information. The bias of polarized angle measurement is analyzed based on the system, from qualitative and quantitative point of view. The quantitative influence on polarized angle measurement and polarized navigation are achieved.