On the basis of the interference theory, by decomposing the single wave beam, the transmission of polarized light passing through a rotating Taylor analyzer is calculated. By transforming the comparative position of incident light, the normal direction of light transmission plane of the prism, and the normal direction of the glued plane into geometric model, the relationship of incident light and the rotating angle of analyzer is given, according to which it is succeed in explaining the cause of “minute fluctuation” appearing along with the transmission curve of polarizing prism.