The wedge depolarizer was usually used as a depolarizer for monochromatic light, but the absolute monochromatic light is inexistent. In this paper, the depolarization effect of the depolarizer for polychromatic linearly polarized light with different spectrum types was discussed. The spectrum of incident light included Gauss, Lorentz and Rectangle. The relationship between the DOP (Degree of Polarization) of emergence light with the radius of incident light beam, central wavelength, angle of structure of crystal also discussed in detail.