In this paper, preparation new type of nanocomposites may be considered as promising materials for different electronic and optical applications such as solar cells, sensors, electronics gates, transistors, lens, lasers ..etc . The nanocomposites were prepared with different concentrations of polymethylmethacrylate (PMMA), aluminum oxide (Al2O3) nanoparticles and of silver (Ag) nanoparticles are (PMMA0.98-(Al2O3)0.02)1-x/Agx where x=.0, 0.02, 0.04 and 0.06. The structural and optical properties of (PMMA-Al2O3-Ag) nanocomposites have been studied. The optical properties of nanocomposites were examined in wavelength range (220-820)nm. The results of optical properties for (PMMA-Al2O3-Ag) nanocomposites showed that the absorbance, absorption coefficient, extinction coefficient, refractive index, imaginary and real dielectric constants and optical conductivity of (PMMA-Al2O3) nanocomposites are increased with the increase in silver nanoparticles concentrations while the transmittance and energy band gap decrease with increase of the Ag nanoparticles concentrations. The results showed that the (PMMA-Al2O3-Ag) nanocomposites are promising for different optoelectronics applications.