In this paper, the (PAAm/Y2O3) nanocomposites was prepared via casting process with different contented of Y2O3NPs (1, 3 and 5wt.% ). The opticalproperties was investigated. The optical characteristics, such as optical density, coefficient of absorbance, index of refraction, coefficient of extinction, dielectric constant of real and imaginary and optical conductivity, showed a growing trend with increasing Y2O3 NPs concentration in the experiments. However, when the concentration of Y2O3 NPs increased, a reduction correlation was seen between these two parameters (transmittance and indirect energy gap, both allowed and banned. Finally, from this result can be used these nanocomposites as the photodetectors application specially in the UV region.