A novel 5-in. R.G.B densely packed poly-crystal MgAl2O4 (magnesium-aluminum-oxide) phosphor screens with multi-layer interface filter have been developed. The filter is a multi-layer alternate high and low index of refraction film which was fabricated by depositing high index of refraction of titanium oxide and low index of refraction of silicon oxide. The 5-in.R.G. B densely packed poly-crystal phosphor screens with the filter have 60% more luminance than those of common R.G. B poly-crystal phosphor screens, and the area of their chromaticity is almost 10% larger than that of common poly-crystal phosphor screen. The 5-in.R.G. B densely packed poly-crystal phosphor screens with multi-layer interface filter are fabricated by using a centrifugal sedimentation method. The resolution of densely packed poly-crystal phosphor screen with multi-layer interface filter is higher than that of conventional poly-crystal phosphor screen. An experimental 52-inch TV set adopting the set of 5-inch densely packed poly-crystal projection CRT with multi-layer interface filter has very high resolution of 2000 TV lines and 1800 cd/m2 luminance, and it is easy to realize the HDTV display.