The scattering of sunlight during its transmission process in the earth's atmosphere has inherent polarization characteristics. Therefore, utilizing the polarization state distribution of atmospheric scattering and its corresponding relationship with the geometry of solar irradiation and surface observation, provides the possibility for navigation in the earth's atmosphere. However, the change of atmospheric composition caused by meteorological changes can directly affect the distribution of light scattering, further affecting the positioning accuracy based on the distribution of polarization state. So, in practical application, the accuracy of polarization navigation guidance is greatly affected by atmospheric conditions. In order to study the inherent mechanism of sky polarization state change under different meteorological conditions, an automatic measuring instrument for sky VIS-NIR spectrum polarization state was developed. The instrument can measure the spectral polarization state of the sky in a fixed time period and in a fixed sky area according to the settings, and adopts a non-imaging measurement method of time division polarization and simultaneous spectrum division. The instrument is mainly composed of a polarization analysis module, a positioning drive motor, a miniature spectrometer, a GPS positioning module, an embedded acquisition control module, a 2-D load turntable and other parts. Its spectral range is 390-960 nm, with spectral resolution of 1.5 nm, observation field of 3°, spectral linear polarization measurement accuracy better than 98.85%, polarization angle measurement accuracy better than 0.1°, and single-point observation time less than 9 seconds. Throught laboratory calibration and field tests, it has been verified that the instrument can stably observe the sky spectral polarization state under various meteorological conditions, and its measurement data can be used to study the influence mechanism of sky polarization state.