In this paper, the application of new functional nano-material films prayed on transmission display screen is studied. Optical properties, such as luminance gain and scattering angle, of the screens are measured to investigate the particle size effects on the properties. The results show that the optical properties of screen sprayed with nano-material film improve notably compared with those screens with films of conventional particle sizes. When the particle size is less than 100nm, the gain is high and the viewing angle low. With increasing particle sizes, the characteristics of screens vary with particle sizes. In order to solve the contradictory relationship between gain and viewing angle and to obtain screens with desirable optical properties, suitable nano-particle sizes ranging from 400nm to 700nm should be chosen for the spraying film. The scattering mechanisms between nano-particles and light are also discussed.