Light absorption by the water column plays an important role in the spatial and temporal distribution of light attenuation, mixed layer heating, primary productivity, and phytoplankton biomass in the water column. The absorption properties of water components are the main influences of the underwater light field and surface spectrum. The study of the absorption properties of the water body contributes to the understanding of its optical properties and the remote sensing inversion of water quality parameters. The effects of light source polarization on the spectral absorption coefficient measurements of colored dissolved organic matter (CDOM) and total particulate matter (TPM) in water were investigated by measuring the polarization of the light source in a UV-Vis spectrophotometer. The results show that the light source of the UV-Vis spectrophotometer is significantly polarized, but the effect of the polarization of the light source on the measurement of the spectral absorption coefficients of CDOM and TPM in water is very small and almost negligible.