The degree of polarization (DOP) of backscattering light in intralipid were measured based on Stokes vector. The characteristics of DOP were investigated when the interaction between polarized light and scattering midum were taken into account . The polarized light included three different wavelengths of 532 nm, 650 nm and 780nm. The diameter of scattering particle was 325 nm. Experimental results show that the circularly polarized component in backscattering light is more than the linearly polarized component for linearly polarized incident light of wavelength of 532 nm. However, this conclusion is reverse for wavelength of 780 nm. In addition, the circularly polarized component is more than the linearly polarized component for three different wavelengths when circularly polarized incident light was used. Furthermore, the total DOP value of 532 nm was larger than that of 650 nm and 780 nm respectively. Linearly polarized light maintained polarization better than circularly polarized light, however, the penetrating depth through scattering medium of polarized light was short. So the imaging used backscattering light can be applied to image superficial objects. Besides, the imaging quality can be improved if the wavelength of incident light is a little bigger than the diameter of scattering particle.