Scattering and polarization properties of particles, such as O2, N2, CO2, water droplets and aerosol, were analyzed by the Mie scattering theory. The theoretical skylight polarization patterns were simulated with different particles and analyzed by making comparisons with real-time measured results. Systematic theoretical studies on the particle′s scattering and their influence on celestial polarization patterns were performed. The absorption and scattering coefficients of different particles were diagnosed with different sizes and complex refractive indices, also were the polarization degree and intensity with different scattering angles. Through the comparisons between measured results and theoretical models determined by gaseous and non-gaseous particles, the conclusion was got that the celestial skylight polarization patterns were mainly decided by gaseous particles while the appearance of neutral point near horizon and the attenuation of polarization degree at low sun elevation were induced by non-gaseous ones.