The relation between the polarization index and the liquid density can be established in term of refractive index. USB2000 spectroscopy was used to obtain the hyperspectral polarization information of brine with different concentrations, and the briny density was calculated. It is found that the optimum wavelength bands of light incident at different angles are different for brine with different concentrations. The precision of the briny density calculated in the best bands is the highest. The best bands become wider when incident angle approaches the Brewster angle, which can satisfy the demand of the present remote sensing technology. The results provide a new scientific basis for monitoring the density of water by using remote sensing technology.