Based on the fundamental theory of the vertical vibration decomposition and synthesis, combined with the Fresnel refraction formula and Snell’s law, the variation relationship between light intensity and energy flux transmittance have been simulated by using MATLAB software, and the polarization characteristics of the refracted light has been analyzed when the natural light and partially polarized light incident on the interface of two isotropic media. The research results show that when the incident light is natural light, the polarization degree of refracted light increases monotonically with the increase of incident angle, but it is always less than 1, so the refracted light generally becomes partially polarized light. If the incident light is partially polarized light, when Is < Ip (k < 1), the degree of polarization also increases monotonically with the increase of the incident angle, but is always less than 1, so the refracted light is generally still partially polarized light; when Is >Ip (k > 1), the degree of polarization of the refracted light decreases monotonically with the increase of the incident angle when the value of k is larger, and when the value of k is smaller, there will be an inflection point position where P= 0 in the curve of the degree of polarization varying with the incident angle, which means that there will be a special case of natural light in the refracted light. These simulation results can not only help readers better understand the relationship between light intensity transmittance and energy flux transmittance, but also help readers more intuitively understand the variation law of the polarization state of refracted light at the interface, even provides more data support for the design and application of polarized light.