Existing theoretical models of skylight polarization patterns have problems that only consider the influence of the sun or the moon alone and could not adequately describe the polarization patterns of the sky during the transition between dawn and dusk in clear weather. Therefore, a modelling method of skylight polarization patterns under the influence of dawn and twilight is proposed. The method introduces the influence of the sun and the moon and calculates the Stokes vectors using the position of the sun and the moon. Considering the factors of multiple scattering of atmospheric particles in the actual sky, the influence weights of the sun and the moon are determined by Stokes vector optimization. In addition, the obtained angle of polarization is used to characterize the skylight polarization patterns. The experimental results show that the simulation results of the proposed model and the measured angle of polarization have the same distribution and variation characteristics, and maintain a high degree of similarity, which can effectively characterize the skylight polarization patterns influenced by dawn and twilight.