Abstract: By investigating the polarization states of object light and reference light in Fresnel hologram, It is found that the linearly polarized laser becomes “partially polarized light” after it is scattered and diffusely reflected by the objects with different material surfaces. Almost all the targets have obvious depolarization phenomenon, and the coherence degree of interference fringes formed by the linearly polarized reference light and “partially polarized object light”, which is actually recorded on the holographic plate, are lower. The great decrease of object-light polarization degree influences the contrast of interference fringes and the noise of hologram. An experiment scheme and testing beam path are presented in this paper. A 1/4 wave plate was inserted into the reference beam path to make full use of the luminous energy of nonpolarized object light to enhance the contrast of fringes, eliminate the polarization effect of object surfaces and improve the quality of holographic record.