To explore the skylight polarization patterns during twilight, the effects of sunlight and moonlight on the skylight polarization patterns during twilight were investigated. First, the polarization patterns of sunlight and moonlight were simulated by matlab based on Rayleigh scattering theory and the differences between them were analyzed .Then, the polarization patterns during twilight were measured by a full-sky imaging test system and the polarization pattern distributions during twilight were obtained on a good day. Finally, the test results were compared with the simulation polarization patterns of sunlight, respectively and moonlight and the effects of sunlight and moonlight on polarization patterns during twilight were studied based on the positions of the neutral points, the number of neutral points and the direction of the meridian. The results show that the tested polarization patterns are in agreement with the theoretical polarization patterns of sunlight, which concludes that the polarization patterns of sunlight play a major role in the polarization patterns during twilight.