The optical characteristics of nano-ZnO pressed disk are studied in this paper. Our study theoretically and experimentally introduced the related theories of the characteristic of laser signal reflected from nano-ZnO pressed disk, the effects of absorptance and transmissivity at different temperature field and roughness of surface. It has been found that nano-ZnO pressed disk has strong absorption peak at near 380 nm, but also the absorption peak decreases when disk's temperature increases. The surface topography and roughness properties of nano-ZnO pressed disk have been studied with atomic force microscope (AFM). Laser speckles are studied with semiconductor laser which wavelength is 650 nm. The tribological characteristics of ZnO nano-particles as lubricating oil additive were studied. The performances of antiwear and friction reduction in lubricating oil are markedly improved by adding ZnO nano-particles and dispersants together.