Influence of nanoparticles of transition metal oxides on varnish samples has been investigated. The nanoparticles prepared by powder metallurgy method, followed by calcination at 70℃. The nanoparticles of ZnO, Al2O3 and TiO2 added to varnish with contents of 0, 0.1, 0.2, 0.3 and 0.4 to study the structural, morphology, dielectric and optical properties. X-ray diffraction data shows different crystal structure as well as particle sizes and ship. Optical properties were investigated using Raman spectrum and UV/Vis spectroscopy, which shown different spectra of Raman and absorptions for all samples. Moreover, dielectric properties data of the samples confirmed enhancement of varnish properties with doping level and types of metal oxide nanoparticles. Based on the experimental results, the additive of metal oxides nanoparticles for the varnish is good for electric motor insulation layers application.